I'm a Londoner who says barth not bath, farst not fast, onvelope not envelope etc whilst DP is a midlander who says the opposite (he's also a haitch not aitch person although I think that might be deliberate!).
Our DD (5) is learning phonics at school. Phonics seems to only cater to the more northern pronunciation of words. Locally it's a mixed bag but DD is leaning towards northern much more now she's back at school.
I wonder how children learning phonics in the London area speak and read aloud? Are they all going more northern? And how do couples with totally different accents and therefore pronunciations, feel about the way their children pronounce things? Do they teach them both and let the chips fall where they may? Or follow the local way, which isn't really helpful in our case.