You will need to apply for an extension before the stamp in your passport expires. The best way to do this is the fast-track service.
The Student Advice and Welfare Services (SAWS) offers a special student service which - in most cases - significantly speeds up the process of extending a visa. You will need to make an appointment to see a SAWS student adviser who will explain the process and check that the service is appropriate for your visa. You should contact SAWS at least six weeks before your visa expires.
Please be aware that many students need to extend their visa in September and October - you may wish to contact SAWS well in advance of your visa expiration date, so you can start collecting the documents that you will need. The cost for the student visa extension application is £295.
Contact Student Advice and Welfare Services for more details.