Been there OP, the shock itself is like a wake up call.
Living in London is a completely different situation to the rest of England tbh. I don't think I ever experienced racism in London, apart from inbred kids when I was growing up.
In my experience the worst kind of racism is the covert kind. You can consciously feel that your the "other", people make subtle jokes, leave you out of conversations etc, it can make you feel subhuman almost.
As nice a place England is I think that there still exists an underlying culture of racism which wont go away no matter how diverse it gets, though I always wanted to live here when I grow up the more I see more of it the more out of place I feel.