unless you want to be a news announcer, and even that isn't as important as in the bad old days, received pronunciation is not going to alter your position in society. Clarity of speech and correct use of language is the important thing. These days, emphasis for TV and radio announcers is to use regional accents, providing they are not so broad as to be unclear.
I've even heard 'skedule' for 'shedule' (schedule) from some news announcers, I haven't yet heard 'lootenant' except on USA films.
Just train yourself to form the words confidently and clearly, you'll be all right.