I actually tend to use the one at Brixton Rec. The changing facilites are not that great (and they're being refurbed at the moment, so even more cramped than usual), but it's on the P4 bus route and the pool itself is nice. Although it's not the cleanest of pools I found it better than the pool at East Dulwich. I recommend it if you want to do some serious lane swimming as it doesn't get that busy. It costs roughly ?3 a swim.