I did mine at the Scottish National Watersports Centre at Cumbrae on the Clyde, very professionally run course, just two of us on the course. Run by David Frame one of their senior instructors who also runs safety for all the big regattas run at Largs so a very experienced instructor. Highly recomended although a bit of a treck for you from the south coast but easy enough to get to by plane then train to Largs and then ferry and a fantastic setting.
They have a course in mid-March which was when I did mine, jolly cold
so take a dry suit as you will end up swimming, we ended up taking turns to sail and capsize the dinghies and then rescue them!