rob_e

Mk2 vRS is a "1Z" not a "1U".  Looks like they've used mk1 octavia settings.

axle weight sticker is inside the door..:
 
http://new.skoda-auto.com/en/mini-apps/owners-manuals/Pages/octavia.aspx?requestOwnersManualOnlineVersion=en/Octavia_5E/11-2012/Manual/Octavia/online&requestOwnersManualLanguage=en&requestOwnersManualEditionDate=11-2012#!pageId=00503
 
"The type plate Fig. 185 is located on the lower part of the column between the front and rear doors on the driver's side"
 
if its a vrs it'll be 55mm.

yep, both good upgrades.
OEM skoda wishbone/control arm is pressed steel where the S3 and TT arms are alloy. Any weight saving to be had is going to be a good thing.
S3 arms are the same as those fitted to the cupra and are geometrically identical to the vRS items, so you just get the benefit of the weight reduction. I fitted mine in conjunction with adjustable ball joints so you can run some negative camber on the front which helps the car turn-in better. If you fit them with your std ball joints the only benefit you get is weight saving. If you fit these with the S3/Cupra console bushes (solid bush vs. voided on the vrs) this gives you a little more precision in the steering without any noticable loss in comfort.
TT arms are also alloy but slightly different geometry so on a vRS they'll give you a change in caster (wheel further forward in the arch) which is great for handling but can cause you a problem if you run wider rims or non-oe offset - you may get very close to the arch or rub - that's the reason i took mine off. To fit the TT arms you need the TT ball joints which are adjustable. Even at their min setting these give you around -2degrees negative camber at the front. Handles great with this but it's a bit extreme for a road car. If you do a high mileage with that much camber you'll be replacing front tyres earlier than you'd like as they'll wear their inner edges.
I had the TT arms but with my wider rims/lower offset i was very close to rubbing on lock/over bumps and the camber was a bit too extreme for me. I swapped for the S3 arms with adjustable ball joints which works better for me.
If you don't do a high mileage and you really want the ultimate handling, go for the TT arms provided you're stock or near stock dimensions for your wheels.
If you're not wanting to go that extreme, go for the S3/cupra arms.