I have checked the BGA website and have found the the Midlands Gliding Club, Wrekin GSA and Staffordshire Gliding club are the closest.
I'm pretty sure Wrekin is a Services club, and thus civilan membership is likely to be by invitation only.
I've not flown at Staffordshire, but believe it to be a normal-sized gliding club (my guess would be 2 or 3 2-seaters, 2 single-seaters).
Midland at Long Mynd is much larger, with palatial clubhouse and a fleet at least twice the size. More expensive I'm sure, but 7 day a week operation in summer.
The obvious thing is to visit each of them, to find out how you like the feeling of the club and whether there are major travelling differences. Some people like the small group of mates atmosphere of a standard-sized club, whilst others prefer the more organised/professional operation at a larger club.