OP- On a technical point for removal of battery terminals.( From my days as a Telecoms engineer, with fore runner to BT, in old days when we had to maintain our vans and had to go through a safety brief with garage manager).
To remove.
disconnect the Black lead first. ( Battery negative), This breaks any possible circuit from the +ve to the body of car. Meaning that ( after negative is removed) the +ve terminal is left floating with no reference to the car body.
To replace
Connect +ve terminal first.
Doing it this way means that ( once negative lead is removed), if your 10mm spanner( on the positive) touches body ,then there's no chance of a nasty surprise ( as in sparks and burnt metal).
Ideally you should use an insulated spanner, but I've found on my 1.4TDi that a ratchet spanner from the likes of ECP is too short to cause problems. For the clamp bolt ,I use a long extension bar, but cost wise it might benefit you to buy a few short ones .
Price wise, you may pay a bit more going to GSF, but I'm looking at an 096 battery prices, where they deliver free and for a Yuassa, with higher everything than one for a petrol car.
First time I changed a battery on this car, I noticed a spark and was worried so I removed lead and checked the current. The spark is caused by ( what I'd suspect) is start up current for electronics starting up and reduces rapidly in less than a minute.Nothing to worry about, and as said, no chance of a shock.