The majority of British people I met in the cities were just fine.
London is beautiful, but yeah, there are a lot of immigrants from the middle east and Pakistan. Saw several with full face burkas..only saw their eyes (which is just ridiculous and a saftey issue).
Tons of Polish too but they seem to assimilate much better, the ones I saw work hard and weren't trying to change the country to fit them. Lots of Polish workers in hotels and resturants when we were there.