If you're white European then you'll be fine.
If youre BAME then the SE is better for you.
Yeah. You'll definitely find more diversity and less racism in some virtually all white south eastern hamlet than you will in, like, Central Manchester.
Honestly, people are daft sometimes. Compare urban with urban, not urban with rural (and the same is true of the public transport btw: living as I do in Manchester less than a mile from train, tram and busy bus route, I laughed at ifailed's description. That's not to say we don't suffer from underinvestment as a regional whole, we do and that's a huge issue, but that is not an accurate description of the whole of the north, anymore than Cornish bus services are of the south).
I mean, I have family members from Ireland who were treated as curiosities in the more rural south east. Ireland! It would be a cold day in hell before that happened in Liverpool or Manchester. I won't even tell you what some of my black cousins have experienced.
I would say the main thing for people to consider is jobs, closely followed by ability to get back into London if you decide you don't like it. If you're going to live rurally, yes transport, but that's true of most of the non-urban UK. I'd budget for two cars, living where OP wants to.