I did NVQ II Beauty Therapy and I thought the make up training we got was rubbish, so I did the 3 day bridal course (I did the fashion one last year for fun more than anything).
I think it was definitely worth it. I was already fairly confident with make up, even after crap NVQ training but this taught me loads. For someone who's not done ANY training whatsoever it might be worth doing a foundation/basic course first, as they don't go into depth about colour correction and application techniques really.
But as you've already done a foundation course, I would think a short course would be fine. After that it's all practise practise practise!
I've only recently started trying to make a go of this professionally, I've done a few weddings but nowhere near as many as I'd like. I'm working on marketing myself. I am confident in providing bridal & occasion make-up, but it's not easy getting your name out there.