This woman does 17 British accents (well, she cheats a bit and jumps over the Irish Sea a couple times). I’m an American, and a Yankee at that, so I’m a poor judge, but a few of them sounded a bit off. Also, I know she isn’t hitting all the variations: there were people all over the UK who’d say something to me in a particularly thick local speech variant, and it just sounded like Dutch being gargled through a misfiring diesel engine, to me, and that was just Alan Moore.
See? All quite mild and pleasant and not hard to listen to at all.