Sounds like you had the same shortlist as me! I also have a good impression of BGS but, like you, prefer the residential option. I also considered OAT as they seem to be the "daddy" but I worked v.hard for the money for this and I want to maximise it. I know many people will say "you get what you pay" for but I hope with hard work and dedication LGU should be adequate.
Thanks for the info on the revision pack. I'm pretty sure I have the aptitude for it and I have P&A Maths and Physics A-levels but it seems a long time ago! (10 years!!). Could do with a refresher!
I'll let you know what I decide and maybe we can be study buddies!