If you like the concessions at Topshop, then you'll love this place. The Laden Showroom in London's Brick Lane is home to loads of independent and up-and-coming designers. And if you aren't close enough to go and have a look for yourself, you can order pretty much everything they have in store online.
P.s. If you're an aspiring or amateur model, or just want to give it a go, they're looking for new faces to star in their future campaigns. Details of how to get in contact are on the blog. I was asked but I'm not sure!