A General Election will be held in the UK on December 12. British citizens who have been abroad for up to 15 years (and were previously registered to vote at a UK address) can register as overseas voters. Further information can be found at https://www.gov.uk/voting-when-abroad
If you are in Portugal and are eligible to vote in the General Election on December 12, you have the options of voting by proxy or by post. The British Embassy recommends that you consider voting by proxy (nominating a suitable person in the UK to vote on your behalf). It takes time for a postal vote to be delivered, completed and returned, especially if you live abroad.
If you want to vote by proxy in Great Britain, the deadline for your local Electoral Registration Office to receive your proxy vote application is 5pm (GMT) on December 4.
If you want to vote by post in Great Britain, your local Electoral Registration Office must receive your postal vote application by 5pm on November 26, in order to send your postal voting pack to your overseas address. Your postal vote must then arrive at your Electoral Office in the UK by 10pm on December 12.
You cannot vote by post from abroad if your registered voting address is in Northern Ireland. If you are registered to vote in Northern Ireland, your application to vote by proxy must be received by 5pm on November 21 by the Electoral Office for Northern Ireland.
If you are an overseas voter, you should renew your registration every year. If you have not yet registered to vote, the registration deadline for the forthcoming General Election is midnight on November 26 (GMT).