You’ll need to send an identity document by post to prove your identity.
If you do not have a UK passport or a share code Do not send a physical identity document. Choose the ‘something else’ option when you’re asked what you need the share code for. Get a share code from the view and prove your immigration status service. You can prove your identity with a share code if you previously used the ‘UK Immigration: ID Check’ or ‘ EU Exit: ID Document Check’ app when applying: You cannot use the passport number of a passport that has expired. If you have a valid UK passport, write the 9-digit passport number on the application form.
This service is also available in Welsh (Cymraeg). There are different rules in Northern Ireland.