It is very important to be registered with a GP in the UK.
Why> There a lot of reasons to do this. A GP can:
Contact the GP Practice for advice on their registration process, as each GP surgery has their own way of processing them.
[NB: Hint 1. Make sure that your personal information on the GPs (and hospital) computer, is correct. This includes the correct spelling of your name, date of birth, address, telephone numbers, email address, NHS number (more info on that here), and local hospital number if you have one].
[NB. Hint 2. If you move to another area, register with a new local GP and ask your old one to transfer your medical information].