Former

Well done. Yes both are common problems, poor quality modern made, or wrong, new parts fitted and connections. With old cars if there's a problem in an area think of the last time a part was replaced there or work done in that area. If an old part is work it often pays to keep it for a while in case the new part plays up. Well done on using proper diagnostics, plugging machines in and looking at codes is only a start, physical and environment testing is conformation.

My money is on it's an Accumate type of trickle charge/maintenance charger. A photo of it might help with advice on its use with the new (or existing battery). My money is also on if the MoT place sells batteries they will find the existing battery at fault probably correctly so at the moment but it also depends on what they use to test the battery at any time anyway. Last battery that went to a 'recycler' from a neighbour got £8.

ETA: see the Driver's Handbook, usually nothing really to do, just check your electric windows are up before disconnecting to save some little effort.

Short answer - yes. Though I think the battery might be able to be revived given above I think you personally might be best served by replacing the battery. Get a battery of the same type, number of Ah and CCA number (check if the number is EN after it) and install. If you put up a photo of the battery disconnected the details should be on the label(s).

Yes an absolute minimum of three runs of each test circumstances to compare three against three but five or more runs of each would be better, then to average out possibly using the calculated mode figure, or your preference of 'average'. - Mean, Median, Mode, Range Calculator. - https://www.calculator.net/mean-median-mode-range-calculator.html

With Tayna (and others) you don't have to use your reg you can look up from the make, model and year to confirm battery. As far as I can see if Tayna offers you 096 it asks if you have start/stop and if you click yes you are offered EFB or AGM. The only thing I can add to all the advice already given is that you might not be charging your battery with the appropriate battery charger and/or appropriately, if you can give more details on this you may be able to save the cost of a replacement battery (one of the most oversold car parts) - or it might be too late. With the age of your car and your lack of use personally I think it's even more important to have a good quality battery not less. I HATE any car that won't start and these over-complicated, over-intrusive, intertwined VW computer programs (especially VWs with start/stop) already have the potential to mess you around without you provoking them more with battery or connections issues, they will make you suffer for it. After safety items one of the first things I checked with a car new to me was the battery it was either charged or if any doubt replaced.

Is this journey consumption or instant consumption? I do not know if there is anything on the car, from which the TC-6 takes its information, that can be as consistently accurate and precise as you rely on. I think you need to have a plus and minus margin of error for all the figures you compare. I do not know but wonder if there is may also be also a margin of error within the TC-6 which would compound the margin of error. These margins may be small (or not) but so are some (not all) of the differences in the figures you compare. My wife's 2015 Fabia engine on a cold start can sometime seem to be running rough and idle high, but not always, I ignore it and take it as the computer programs getting their panties in a twist. My car isn't always sweet on its (full mechanical) choke running either - but that is more my guesswork about how far to pull the choke cable out each time.

Don't be fooled by former glory with brand 'names' sometimes the name is all that's really left with company takeovers and brand names bought. Seek current reviews and advice. Brembo I heard a few years back weren't the quality they once were. EBC is a local family company whose products I've never bought, or used AFAIK. Pagid is a brand of the TMD Friction Group who also have Mintex among others. I fitted Pagid pads and discs to the front of my wife's Fabia and they seem a good product, braking feels good. I've never owned drilled or grooved discs and never felt the need, but my cars were generally lighter than a Mk3 Fabia, I prefer good pads (shoes) and tyres. If you are also doing the front my Topic might (or might not) be of use to you. -

Things haven't changed, you don't go German if it's available from the Japanese.

You are now qualified as a VAG Design Engineer, German engineering excellence. 🤣

Plus possibly delayed warming and more (hopefully) burnt fuel products to engine and its parts and to the cat.

Neither fully trust any single database or source of information (especially from me) always cross checked . As has been put Comma Xstream® G40® is Glysantin® G40® by BASF and listed as VW G12++. Yes the cause of coolant level dropping needs to be confirmed. Coolant specification seems to be another example of VW (VAG) not being as clever as they think they are and changing their minds even as far back as the year 2000. I really think they need more photos of human body parts to help them know differences. My wife's 2015 Mk3 1.2 TSI petrol has G13 on the tank but I was told it's now G12evo (not to be confused with G12+ or G12++). Coolant is now getting like oils with particular specifications by manufactures like VW, how much of this specification is justified I don't know as I was told by someone that worked for at a VW garage that "G12evo is the latest and greatest and will mix with all previous vw coolants" though I'm not sure if that includes G11. I think we had five different types of coolant without counting the sub divisions of manufactures specifications of those. As well as @rum4mo's BASF's numbering system (which is missing G12+ whatever that is) here 's a chart to add to the general (VW/VAG) coolant confusion.

At £1.25 each for plug and washer combined I got (two) box(es) of these, I know it's waste of materials but finding the washer in a reasonable quantity at a reasonable price was beyond me and I've already too many different washers and fixings spare that just take up space rather than use. As happens often with VW (VAG) there was a change of mind (confusion) by them as to which engines needed which plugs and when but AFAIK this fits the 1.2 TSI engine and whatever number and code that is. As at today, £6.25 for quantity of 5 -5 Oil Sump Drain Plugs - VW Golf Polo T4 T5 T6 - N90813201 Febi Trade Pack 48871 - https://www.ebay.co.uk/itm/174613262625

Personally I usually wait around 10-20 seconds before driving off but that is as much about listening to all the car noises for anything unusual or new, to check the warning lights and gauge readings, including the rev-counter, and even if something might smell odd. To have the car sitting static at fast idle is wasting fuel, you might as well have the car moving using that fuel. In 1st and 2nd gears you are probably at more than say 1,500 rpm when driving the car so above the fast idle speed anyway. There is no need to drive slowly, obviously you will also not want to drive too quickly until the car is fully warmed. You want to get the engine up to operating temperature as quickly as possible which usually means driving in the appropriate way given the conditions you face. Do you have an oil cooler, if so is it larger than standard?

For other viewers that might be wondering about a refractometer and its use, a simple explanatory video. -

Not really weird, basic servicing and maintenance like changing the engine oil & filter are important and effective, but can only do so much to reverse any previous neglect and/or abuse. Much servicing and maintenance boils down to simple clean and lubricate, oil changes a good example of both, even erasing error codes is a form of cleaning. Many think they can ease up on servicing and maintenance on older cars when usually it's needed even more. Keep up with the oil and filter changes and use good quality oil and filter if you want to have things last as long as possible. Also timely air and fuel filter changes will help as well as, where appropriate cleaning MAF and throttle body. Unless everything is reasonably clean you can be moving and promoting 'dirt' around the engine, which will eventually grind or clog items.

Fair enough just looked a bit untidy and as if it should go under the throttle cable, been thrown up like a quick washing line, same as a Sky satellite or cable TV installation we get here, speed of installation matters only.

If it's witchcraft keep it to yourself! Cheers.

Yes but it is four halves. 😄 Cheaper and better for your health and life to stick with a low tolerance, and you'll have a clear head for sorting your car.

Listening and watching, all too much and too fast for me, but now you've pointed it out and I've replayed it twice (can't watch both dials at once) yes I did see it, well both. Fair enough. Tell your Grampa you've been told to put a shilling in the meter. All the best for Saturday it'll be interesting to see what you find and what it turns out to be, good luck.

I'm stone cold sober, I only social drink once or twice a week for a few hours, and it's not today, I don't do drugs either, just high on life at the moment, it won't last too long I'm sure. The vultures might circle overhead but they won't come down for a living body, even if they keep an evil eye on it. 😁

Is your power steering via battery power per chance. Just tell everyone you were stopping to let pedestrians across 😁 As I remember it you were told, not by me, that wouldn't effect the clutch, you must have been dreaming again. (note: I'm pulling your leg). All I could hear on your 6 seconds video was a car starting. You'll sort it, perhaps best not to drive the car until Saturday if you're worried.

Different to what I've seen but I'm not splitting hairs if I've not given strictly correct terminology, or comprehensive explanation, at the moment I'm not in the mood, Glen Miller will have to wait and I've been here before and fed up with the full half hours or £8 course of ten that run here. -

Have you tried Autoglym Bumper & Trim Gel, expensive in the shops but it can give good results - but not perform miracles - apply with an inch and a quarter (30mm for younger viewers) cube of (clean) bath sponge (cut precisely and it won't be noticed missing). Leave to soak, Bumper & Trim Gel that is, and wipe off (buff up if you must) excess. Nice smell now too. - BUMPER & TRIM GEL -https://www.autoglym.com/bumper-and-trim-gel Or there are these ones you get with a sponge and apply adverts on YouTube, I've never tried them but you used to get similar stuff decades back and they were alright, forget the names.

Guess what I start with! How are you measuring the battery and what with. Did you also check the alternator readings. Checked the battery connections and earth(s) for condition and security. Did you sort your previous clutch issue. Yeap check for fault codes but if there aren't any it proves this is all in your imagination or you're dreaming and might wake up soon, definitely dreaming about milk going off on a warm Scottish July day.