I've got to add my two cents...
I'll tell you the place to go is Blades!!!!!
http://freespace.virgin.net/blades.sports/ I bought from them several times when I was in Wales and England, and they are a pleasure to work with. They have an excellent selection, friendly people who know their stuff, and are pretty much as close as you get for London. Just beware, the parking lot is an icerink in winter! They did a lot for me when I was there... first time I actually got all my kit to fit right! And NICE stuff, too. Been very happy with them, so I try to pass along a good word.
Enjoy London, I'm envious, I'd love to go back!
