Unless you're doing some artsy degree like English Literature, you're pretty much guaranteed a two-year visa after graduation. If you get a job within two years you can get your employers to sponsor long-term visas.
It's quite hard to be out of the league of most UK universities. You pay 3 to 4 times the local students and they like that money. They'll bend requirements to accept you and they trust that Asians will work their asses off to make up the difference.