I'm trying to find a venue to have a gig/party for my 30th birthday party in April and would really appreciate some suggestions.

Ideally I want somewhere that's

a) Free to hire
b) Central London (or at least easy to get to from North or South London)
c) OK to have bands and DJs.
d) Ideally open 'til at least 1 in the morning.

I've tried the Miller, which would have been ideal except they're not free on the night in question, and have considered a few other places but they don't feel quite right. So, any good suggestions?