here in poole we have three swimming pools and each one has a morning when the over 60s can swim for free - each pool has a different morning so you could really go swimming three times a week for free!
and our council does a scheme called "access to leisure and learning" for those people on benefits [pension credit, dla, etc, etc]. it costs about £2.50 a year for the card and you can then get discounts on swimming [outside the free swimming times], theatre performances and also courses which they run around the town.
i used to go swimming once a week with a friend but unfortunately she passed away so i haven't been for a while as i don't like swimming on my own. and, for almost a year now, i've had a severe problem with arthritis in one knee and cannot walk from the changing room to the pool without a walking stick and there's nowhere to leave the stick beside the pool!