As above, i'm looking at some new wheels-18"s, and i'm thinking they will look that much better if i get the car lower.
I've read to see a noticable increase on the S-line 40-50mm is the minimum you should look at.
I've seen these;
Audi A3 1.8 TFSI 03-11 H&R 45mm-50mm lowering suspension springs kit | eBay
I'm in SW London aswell, I'd even go down the route of buying them through the garage that were fitting them to save hassle if anyone had any reccomendations?