My pronunciation is generally very very good, with a few kiwi-vowel-fail exceptions from time to time. When I spent time in England I was most disappointed to find out that, unlike Sir David Attenborough, most people there can't speak English at all! What this lead me to was two things: Avoid all locals at almost all costs and simply stay indoors AND focus on improving my speech patterns and skills. As a result, when I got home to NZ afterward, I was accused of sounding British. I'm never sure whether to be horribly offended by that (there are some ghastly accents there...) or pleased (also some of the very best). However it never left, and continues to improve, by force, over time.
Having said (all of) that, there were a number of words that I didn't know how to pronounce at all in there. 21 to be exact, though some are likely a result of me knowing them only by sound, and never having written them, as such that list will shrink once I do some research into it. And once I have, I'll take a crack at it and upload a video just as practice for the new Podcast thing people seems so keen on ;-)