Crash space in London 21 - 24 July?

[liv]

OK, I'm an idiot, I signed up for a four-day text study event on the assumption that it was a residential thing. And in fact it's yet another of those events that are really only aimed at Londoners, preferably those who live in the NW London enclave. So can anyone offer me crash space for any of Wednesday evening (21^st July) through Saturday evening (24^th July)? I should emphasise I'm not expecting to stay for that whole time, but just one or two evenings would give me a chance to socialize with people I like, and also make the event less prohibitively expensive. If I can do two nights in a hostel instead of four, that's a big help. The actual location is Hampstead Hampstead Garden Suburb, but anywhere in London or surroundings would be a start.