I don't think that British pronunciation is that different than American. The only difference I really notice is the difference in spelling like Americas "color" and Britains "colour". If you learn either subset of English both will be able to understand you. :)

As an American, I can tell you that proper British pronunciation (what they teach in language books) is always understood by American speakers, so there's not much to worry about. To most Americans, the oddest thing about other English accents is often how they pronounce the letter R. Most Americans pronounce the R very noticeably. In other English-speaking areas—Britain, Australia, and even the Southern United States—the R tends to be more subtle, barely there at all. THAT's what most Americans hear when they hear an accent.

I think that British pronunciation is more gaodashang than American. The feature of British pronunciation is the short pause between every two words.

I think you should choose the one you like better or seems more clear to you. Good luck!