Sat 10th May - London to Cambridge

Lots of lovely pubs in Campbridge. I used to like this pub right on the river, by one of the pieces (aka parks), can't remember what it's called (anybody? Is it still any good?) but I doubt you'd need or be able to book. Everyone just spills out into the park anyway.
http://www.multimap.com/maps/?hloc=GB|parker's%20piece%20cambridge#map=52.21226,0.12846|18|32&loc=GB:52.20259:0.13123:14|parker's%20piece%20cambridge|Cambridge,%20CB1%201

If you're talking about the Fort St. George, it's currently closed for refurbishment AFAIK. Shame, as their burgers are AWESOME.

If you want something central you could take a look at the Eagle as they'll probably be able to book you some space. Sat 10th is the day after my exams finish so I'll probably be hungover and hence not make it down to london in time to join you, but as I'm in cambridge anyway I might come join you guys in the pub or something...