Since 1 April 2006, all doctors working in general practice in the NHS in the UK (other than doctors in training such as GP registrars) are required to be on the GP Register. This requirement extends to locums.
If you have not completed the UK GP Certificate of Completion of Training programme you will need to apply for a Certificate of Eligibility for General Practice Registration (CEGPR), which will then enable you to be entered on the GP Register.