Funny you should mention this - I was doing my pre-reading work for a CELTA course and there is a section in one of my books (Learning Teaching by Jim Scrivener) that mentions this issue.
He says that R.P. is sometimes viewed as 'the' version of English, however most people speak with accents and to try and teach with a different accent than your own can be challenging. Scrivener says that you should make students aware of the different accents in English. I haven't got the book to hand, but its a good read full of tips (at least I think it is, as a person waiting for a CELTA course to start).
If you want I could record myself XD - do you want a broad Yorkshire accent?
Perhaps look for youtube clips? They should have a whole range of accents on there!