If you are a British citizen living abroad, you can apply to be an overseas voter. You must have been registered to vote in the UK in the last 15 years and be eligible to vote in UK Parliamentary general elections and European Parliamentary elections.
If you were too young to register when you left the UK, you can still register as an overseas voter. You can do this if your parent or guardian was registered to vote in the UK, as long as you left the UK no more than 15 years ago.
You need to make sure you have time to receive and return your ballot papers by polling day. If you don't think you can return them in time, you may want to consider voting by proxy.
Voting by proxy
If you're abroad you can apply to vote by proxy (someone voting on your behalf). You must be (or applying to be) registered individually, and the person you wish to appoint as your proxy must also be (or applying to be) registered individually.
If you happen to be in the UK on election day, you can always vote in person at a polling station.
However, if you have appointed a proxy you can only do this if your proxy has not already voted on your behalf. If you have a postal vote, you cannot be issued with a ballot paper in the polling station but you could hand in your completed postal ballot at the polling station.