get yourself a copy of S&G, Sailplane & Gliding, and look at the ads in the back.
WWW.Gliding.co.uk is the British Gliding Association website and should give you more leads.
You CAN solo in a fortnight but you will need to consolidate with a year or two of 'normal' club instruction/supervised flying. It's just the same as a concentrated driving course, you will have been trained to pass a test, not be a driver. A lot of experience is gained second hand by talking in the bus(launch point control vehicle) and by watching others make mistakes on your behalf so don't try to be too quick. I would personally reccommend learning at a winch launch site. Previous experience on a normal powered aircraft, as opposed to a Motorglider, is a mixed blessing. If you have done no flying at all, learn to glide first. You will be a better pilot for it.
the D.I.Y. clubs which have no paid staff will be cheaper but you are the staff so expect to be on sit at least half a day for a 'set' of flights. Trainees are often given two or even three trips at a time but we at Oxford expect you to be there to get stuff out in the morning or to put it away at night. Professional clubs with paid staff may be more receptive to 'turn up and fly' operation but there is still plenty of work to be done. They will also probably be aerotow only and WILL be expensive, very expensive. You will also not get the 'learn by osmosis' bit.
The initial learning is the difficult bit. It takes a couple of years of committment but you will make great friends and learn a lot, not nesessarily about gliding/flying. After this time, you will be a competent glider pilot and a much better man than you were when you started. At this point you can go and buy a share in a syndicate and start really gliding. You do not have to wait your turn and you do not have to land after one hour. You can hook the trailer to the back of your car and go anywhere you can get a launch to fly.
Gliding is a great sport. You don't have to go anywhere. If you can just keep flying for an hour or six, you have been successful. If you do want to go places, there have been recent flights in the UK of 750 Kilometers. Go for it.
Mike W