Racism is a big issue wherever you are in the UK, but i dont recall ever having been called a terrorist to my face. Dont know who told you about being called terrorist everywhere in birmingham, but from my experience it isnt at all common.
Your correct in that birmingham is like bradford in a lot of ways. There are muslim 'ghettos', just as there are sikh Ghetto's and white ghetto's. I've also lived in Leicester, and it was the same thing there as well. You had Gujrati muslims areas, then you had indian hindu areas etc. Unfortunately, that again is a feature of most major cities that have immigrant populations. The immigrants arrive to the area and settle in the inner cities normally, the white populations move out (for whatever reasons) and what your left with are ghettos.
If you go to London, you will find the same thing, manchester same thing, sheffield...wherever you go its the same.
America...look at the major cities with sizable immigrant populations, you will see areas where theres mainly black african americas, latinos, asians and so on. Dont a lot of the cities have areas such as 'little italy', 'China Town' etc
This is a universal phenomenon......