Are there really THAT many muslims in the UK?

I'm always hearing Brits whining about "the muslim takeover of europe" and how they will "be the majority in 20 years". I looked up the statistics and found out muslims, at most, make up 4% of the population and all the other minorities put together make up only about 10% of the UK. How is that "a muslim takeover"? In america hispanics make up 16% of the populaton, blacks make up 13%, and asians make up 9%. That's about 40% overall compared to only about 10% in the UK. Practically half of Americans are a minority. What do Brits have to complain about?