Coming to London, borrow, rent, buy a bike?

Hello!
I'm from LA and I'm heading to London for a week or so at the end of June 2009. I was wondering if any of you kind folks would lend an experience cyclist a bike. I'm a member of LAFixed, so I thought this might be a good place to search.
Frame size 50-51.
It could be road, fixed, beater, or penny farthing (although i don't know if that's legal in the uk).
I hope to do some local riding, rides, and some local touring.

Thanks so much!
meandmybluebike