Got it done at "The Auto Pool" VAG specialist in Iver, Bucks (only 10 mins down the road).
They were pretty quick (3 hours from when I dropped it off) and not too expensive (about ?150). The bloke who owned it seemed a nice chap too!

They said that the camber and tracking would be OK. I'm just not sure who to take it to to get it checked, becuase the figures for non-lowered cars wouldn't apply, so a normal tyre place probably wouldn't suffice.