If you haven’t received a voting pack from the elections commission, you may or may not be enrolled.
So if you want to vote (and you damn well should), check if you are enrolled on this link.
If you don’t show up on the electronic roll and you are in anyway unsure, then your best bet is to head to your local post shop, and fill in and give them an enrolment form – BEFORE the post shop closes. You can then do a special vote in the morning.
Or you can early vote. However they seem to shut at 3pm, so you don’t have much more time.
Today is the last day to enrol to vote. You cannot do it tomorrow.