I just spent the last 4 or 5 hours talking to a Russian friend of mine who learned British English and there is no way to tell that she learned British English instead of American English by listening to her. It will not make a difference what kind of English you learn because to us you will just sound like a Russian who speaks English.!!!!!!!!!! You will not lose your Russian accent.

Dobry,
Are those British teachers from Liverpool or Birmingham or something? In some areas the accents are thick. What ever happened to Brits with a BBC accent?