Please take a look at the latest circular of UK immigration that comes into effect from October 2011. UK post-study work permit/ visa has become very difficult.
According to this new circular from UK immigration, Tier-1 post-study work visa will be stopped from April 2012.
All students aspiring to work in UK, have to go through the Tier-2 work visa procedure to be eligible for post-study work. While there is no limit on how many such work permits can be issued and the concerned companies can issue 'certificates of sponsorship' to students who graduated from UK and still have eligibility to stay legally in UK at the time of sponsorship,
such work permits still are subject to the condition that suitable candidates are not available from with in UK/EU.
There is a strict procedure the sponsoring companies/institutions have to follow before they can issue such certificates of sponsorship, some what similar to the procedure that has to be followed with regard to issuing H1-B visa in USA.
I think things have become virtually impossible for people to get post-study work permits beyond April 2012.
Please check this out before you make a decision to study in UK, even in the best of the Institutions.