DAR, the moderator, has wise words. Training can save your butt from painful experience.
I started with gliding, at the age of 50, and instructors in most gliding clubs do not charge for lessons! however any club would be happy to welcome a chap with your background and skill. A weekend club in your neighborhood (look up the local ones on the British Gliding Association Website), and just visit and observe before deciding which might suit you. They will have the site, and the knowlege, and probably some well used training two seaters which have benefited from the experiences of their designers.
And who needs an engine? thats what hills - and summer cumulus are for. Maybe as a go it alone chap you worry about permission for using a field for TAKEOFF.... as a cross country glider pilot, it is not necessary to ask permission to LAND anywhere that seems like a good idea, as when you run out of lift, you are technically an emergency.
Just be nice to the farmer.