Unless you respond to the letters sent out by the council about the electoral roll.
You used to be able to ignore them if there were no changes to who can vote. Now you have to respond every time they contact you. Even though you did it what seems like 5 minutes ago, you have to do it again. If you don't get in touch with them you'll drop off the register.
Whichever way you want to vote, make sure you've confirmed your details or you won't be able to vote.