Thread: Swimming

On the same lines as @gimps Running thread who's regularly swimming for exercise?
I like beer, chocolate and all the rest of the shit that's good at building a tyre around your middle. Was thinking a bit of swimming would be a good, low impact way to keep fit.
Any advise on the best way to go about it? Was thinking evenings would be my only option as mornings are too busy and I don't have a consistent enough lunch time to squeeze anything into.