Most immigrants only come here for a better life and to send money home for their family. Look at all the OFWs all over the world.
As for people congregating together with their own compatriots, that's no different from thousands of British people in Spain who live in little enclaves, eat only 'British' food and don't speak any of the local language.
THe only way to stop people wanting toleave their own country is to make it more attractive to stay. How many time have you read on this forum how hard it is to be apart from a loved one? That's how many people from overseas feel in this country and their families at home.
Think about the hypocrosy of the free movement of capital (and where that has landed us) and the controls on the movement of labour. The rich can move their capital to take advantage of cheaper labour/raw materials/fewer employment rights for workers but labour can't move to take advantage of better conditions and pay.
THe ruling class want us to be divided so they can keep us down. The sooner we all realise that the better for all of us.
