Depending on your nationality, you may be required to register with the police when you arrive in the UK. It will be clearly printed on your visa if this is required and you must register within seven days of entering the UK. You will also need to register with the police if you extend your Tier 4 leave to remain (and therefore receive a new visa). You will need to go to the Overseas Visitors Registration Office (OVRO) to register. This is based in Central London:
Overseas Visitors Records Office
323, Borough High Street
Please visit the Metropolitan Police website for further details of how to register with the police, including travel instructions to get to OVRO. You will receive a Police Registration Certificate, which you must keep safe as it will be required if you need to make another Tier 4 application. If any of the details on your certificate change (for example your home address), you will need to get this updated. This can be done at a local police station.