@ramalo
Firstly, any MBA, regardless of country of origin or visa status, will have to demonstrate that they are the best candidate for the job. Depending on the sector, that might not be that easy given the high degree of competition for jobs in the UK, which tends to attract applicants from around the world.
But specifically on the visa issue, I would say that it is very much dependent on the company. Some of our non-EU students have found employment with small UK companies who are willing to sponsor visas. On the other hand, there are international professional services firm who have a policy of not sponsoring visas, whereas their direct competitor might sponsor a visa.
So there are no patterns but it does mean that non-EU students should start their career search early. Advice, which everyone should heed.
Conrad