British citizens can register as overseas voters if they are currently living abroad regardless of when they left the UK provided they meet the criteria
If you were too young to register to vote when you left the UK, you can still register as an overseas voter.
You will need to provide:
- the full name of a parent and your birth certificate which includes the parent's name and their date of birth
- or the full name of your guardian and evidence that confirms the person named was your guardian when you left the UK.
More information is available on the Electoral Commissions website.