You are almost certainly registered to vote - but do you know anyone who is not registered? If so, please pass this on to them.
Registration is easy - and can be done online at gov.uk/register-to-vote (by Monday 25 November). You will be asked for your National Insurance Number.
If you might not be able to vote in person on 12 December you can apply for a postal vote at apply-for-a-postal-vote - but you must do this by Tuesday 26 November.
Your postal vote needs to be with your local authority by 10pm on polling day to be counted. Clearly if you are sending it by post you must leave enough time – but a postal vote can be hand delivered - you can take it (or get someone to take it) - to your polling station or to your local authority on polling day.
Or you can apply for a proxy vote at proxy-voting-application-forms - do this by Wednesday 4 December.