You can register to vote online or update your details on the electoral register:
To register you will need to provide your National Insurance number and date of birth as evidence of identity.
Members of the armed services
If you’re based overseas or think you may be posted overseas in the next year, you should register as a Service Voter, as this allows you to register at a fixed address in the UK even if you move around.
Register to vote as a member of the armed services