Think it has been mentioned elsewhere on the forum, but apparently a good option for overnighting is to join the National Trust? I understand that lets you overnight in the majority of NT carparks and of course gives you a lot of gardens and 'national treasures' to visit.
I suspect those days are long gone, sadly. The nice open air pool I used to go to in the local town (Martins Pool in Wokingham for anyone who remembers that one) has been a housing development for years. Shame really as it had lots of little wooded areas where young couples used to nip into for some 'privacy' :tongue:
Also used to go on family trips to a great open air pool in Camberley - the 'Blue Pool' (now serving the town as .... yup. A housing development)
My primary school had a little 10M pool that you could get a summer pass for in the long holidays and used to go every day - great for getting away from my mum

Of course that is long gone as well. Now part of a housing development for wrinklies.
All Local Authorities are interested in is selling land for houses not providing amenities or facilities.