Another vote for Tayside Aviation from me. Edinburgh, Glasgow & Prestwick are all too busy for PPL training, you'll spend lots of time (and therefore money) taxying and holding. That really only leaves the three Tayside establishments and Cumbernauld. Since you'll probably do 70+ landings in the PPL course the free landings at Tayside is a big bonus. A very important factor is to find an instructor who you get on with and then stick with him/her. Plenty of sob stories around about people who didn't get on with their instructors, but one man's meat is another man's poison.