If you are not able to vote in person, for example, because you will be away on polling day, you can apply for a postal vote.
You can register to vote by post at any time. However, it is best to apply as soon as possible in advance of any upcoming elections. The exact date for applying for a postal vote in any particular election will be advertised in advance, but typically the deadline is by 5pm, 11 working days before the election.
You will not need to provide photo ID to vote by post. There are other identification checks, including verification of your signature and date of birth.