Have you tried joining any groups and the like? Political groups, the WI, sports, craft groups? I've met people doing all sorts of weird things over the years (my new goal is to do roller derby!) Seriously, even going to lectures has allowed me to engage in friendly chats which have led to friendships over time. And most of my friends are awesome feminists, queer kids, activists, artists and general badasses, so there's definitely room to build the environment that you want. And whilst the subtle racism here can be grating, I don't have to worry about being murdered on the streets by cops like in the US, so that's a great bonus.
London has been my saviour in a lot of ways, and I absolutely adore it, but it's also a hard city to break into and lots of people just don't manage it. But you should definitely see other parts of the UK before making up your mind about it. Yorkshire is wondrous, especially the moors, Northumberland is beautiful (spend a winter weekend in a holiday cottage near Bamburgh or Lindisfarne, it's magical). I spent Boxing Day one year driving into Scotland and watching the waves crash against the jagged coast and felt total bliss. I'd also recommend Devon, Dorset and Cornwall for sheer natural beauty (have ice cream in Lyme Regis on the Jurassic coast and your life will change). Visit a nice seaside town and visit a sh*t one, play arcade games and mini golf and you'll feel like a teenager again. I'm a city girl through and through, but I will always jump at a chance to visit British countryside to unwind. And if you want a complete change of scene, it's cheap and quick to visit Europe and North Africa. London is it's own country, for better or worse, it doesn't represent England at all, just like NY and LA don't represent the US.
I just don't think it's healthy to dwell on how much you hate something, especially if you can't change your situation for a while. I've done it on a more micro level (I hate the house I live in and I've lived in it for 8 years with roommates, despite being married for 5) and it made me physically ill and deeply depressed. It wasn't helpful and it made things worse, so I've learned to just view it as an experience that will lead to what I actually want, which helps a bit. I'm no optimist (far, far from it in fact), but sometimes you just have to carve your own niche in order to stay sane. I've been in London now for 8 years and I couldn't imagine being anywhere else (except Berlin, because it's awesome).