Student will have to find a graduate job offer with a sponsoring employer before your student visa expires. Although graduate employers hire all year round, some popular graduate programmes have a long recruitment cycle. You will need to begin your graduate job hunting early in your final year of study to maximise your chances of success with particular firms.
You need to pay attention to how UK graduate employers recruit, and in particular the skills and qualities sought on applications to ensure you are in a position to apply early. Focus upon ensuring your language ability is proficient for job applications and selection processes with employers.
The Tier 2 visa requires a minimum salary of 20,000 for the position, or higher, depending upon the UK Border Agency's Codes of Practice. You'll need to ensure that you have a range of employability skills on offer, and apply early in order to secure a position that pays this salary if you wish to work in the UK after study.
For more information on 'Working in the UK'.