You need to be on the electoral register to vote in the UK general elections. You are not automatically registered even if you pay council tax, so you should check to see if you are on the list of everyone who is registered to vote.
You need to register with your local authority, but there is a great website provided by the Electoral Commission called About My Vote. It will show you how to register to vote and once you’ve completed your form, you’ll need to print it off, sign it, and send it back to your local electoral registration office. You can get their address and other contact details by entering your postcode on the site.
Don’t hesitate. The deadline is tomorrow.