Hey jenny....
You don'y have to be trained with MAC to receive their professional MUA discount. You have to provide two examples of proof that you are a professional working makeup artist to receive 35% off, and beauty therapists receive 25% off (I think, I know they did last time I checked!).
A lot of MUAs are boycotting MAC in the US, not due to to their Pro Discount Scheme, but due to the fact that they are supplying MAC counter staff free of charge (or for very low wages) to NY Fashion Week and such like. This is taking jobs away from professional and experienced makeup artists, who understandably feel rather peed off!
Just thought I'd clear that up.
As far as I know, Bobbi Brown don't have a UK pro discount, Benefit do at 40%, and although Stila and NARS don't have a UK scheme set up as yet, I think they are planning to in the near future, however I have received some fab gratis off Stila and NARS, both shipped from the US! Pout offer 25%, Makeup Forever 40%, Pixi 30% (I think). If I think of any more, I'll post them up.