I have experienced living in London and one other city up north
I've experienced living in several continents, was brought up and educated in other countries and have lived under many different poputical and religious regimes.
You need to know that this is one of the most tolerant and open-hearted countries in the world.
Forget what you've been told and leave it, get out into the world, travel and make friends with people in their own home, not just people who've travelled to yours. Speak other languages, read books, newspapers, in translation if you have to. Get visas, stand in line.
It's all possible.
I'll shortcut one thing for you. Ignore colour and creed. Meet individuals and base your reactions on their humour, their food, their film, sport, whatever you have in common.
Don't believe what biased media want you to believe, left AND right-wing.
And if people say they are unhappy, individually or in numbers, try listening rather than telling them they're wrong, whatever your personal feelings.
Because one day you might need someone to extend you the same courtesy, and if you're not in tolerant old GB, the stakes might be a whole lot higher.
Good luck.