jtaylor wrote:

The first thing I thought of was somewhere near crystal palace - is
that
pool still running? Would there be reasonable accommodations for
such a
group?

Crystal Palace pool is still there and in use, though it's pretty run
down these days. I think it's still officially run by Sport England so
their website might be a place to start. Sorry I don't know any more!

As far as transport to Central London is concerned, the 3 runs from
outside the park all the way to Oxford Circus, and Crystal Palace
station is also convenient for the pool (pretty decent off peak service
to both Victoria and London Bridge). But then I'm biased as I live down
the road and would like to see more proper use made of the sports
facilities!