After puberty, it is inceasingly difficult to pick up an entirely different pronunciation, so sounds in a language that are not found in your own langauge may cause problems, though this does vary with the individual. With variations of your own language, there's a common process called 'approximation', where some people pick up some of the sounds around them and adapt their speech. In your case, you seem to be such a person, so you'll probably find yourself picking up UK sounds and words. I'd do nothing- it'll come naturally.
- For Teachers