Just to reiterate what was said earlier...
Forget glasgow flying club, there well up there own @rse, and as far as I know they have to fly a good bit out of Glasgow to get any training done as well as competeing for runway with all the commercial traffic.
Cumbernauld is a good place, quiet we gaff, not bad, I had a trial there and I couldn`t fault it.
Prestwick is probably your best bet, it seems to be a good laugh down there, and as far as I can make out the training seems pretty good. There is also a small amount of commercial traffic there as well which is good experience. Besides Prestwick is turning into the loony bin for all the Glasgow wannabes which can only be good.
Best to make your own mind up, visit them all!!
Good luck.