Lizz, my advice when it comes to bras is as follows:
1. Different brands fit differently, so experiement a little before you try.
2. Go to a good underwear department and get them to measure you. Preferably get measured by one of the older more experienced women, not a young slip of a thing.
3. At least until you are a better judge of what's going to be comfy long term, buy your bra from a proper corsetry manufacturer. Yes it will cost you BIG time, but what price comfy, beautiful shaped, well suported boobs?!
4. When you get to Britain, I recommend you try Fantasie, Freya (who are part of Fantasie in fact) Charnos, Rigby & Peller (they make bras for the Queen - expensive, but pretty while supporting like scaffolding - you may not have noticed but the Queen is pretty "stacked" herself!) Also, there's a company who operate mainly through catalogues and online called Bravissimo who stock all of those brands and more and are designed for those of us with more than average up top. They are definitely worth looking at once you are sure of your size.
http://www.bravissimo.com/bravissimo/Default.aspx
5. When you get to Britain, remember that British sizes are slightly different and get measured.
6. We can always go shopping together sometime?! Mayhem and Fussy can wonder what's going on in the changing rooms without them! LMAO