Chris Perkins, Senior Producer of D&D, spoke about voice talent in his recent column. One tidbit he touched upon really resonated with me:

"It’s perfectly fine to mutilate real-world accents. So what if your Maine accent doesn’t sound like a real Maine accent. It’s not like your campaign in set in Maine, after all; the players won’t hate you because your rendition failed to conjure memories of summers spent in Bangor."

People will sometimes shy away from accents they can't properly emulate. Why? If your British accent sounds like a mix of Australian and Scottish, who cares? Maybe you weren't trying to emulate a British accent -- maybe you're speaking in a perfect Faerunian accent, which just happens to sound like a cross between our world's Australian and Scottish accents.