Just to give some clarification on a few points on this thread:
The link is legitimate and if you, or a friend or relative, are in the eligible groups in England (over 70, or clinically extremely vulnerable), then you can book. The government is trying to do as many people in those categories by mid February, so you’ll be doing them a favour in reaching the target and getting on to the other groups as soon as possible!
It will only give you options for the large Vaccination Centres, or a pharmacy-led site (which might not be in a physical pharmacy, eg the one near me is in a supermarket). You can’t book at a GP-led site through that link.
There’s a list of all the vaccination sites currently operating here. You can have a look at the ones near you. HH means hospital hub, VC means vaccination centre (ie mass vaccs sites), PCN means primary care grouping, ie GP-led, and pharmacy means pharmacy-led (not necessarily in an actual pharmacy).
You can wait for your GP to contact you if you’d prefer not to go to any of the options on the link on this thread. If they haven’t already, they should soon (assuming you are currently eligible).
One reason you might not be able to book through that link, even if you are eligible, is because the invites are only going to people who live within a 45 min off peak travel time of the big vaccination centres. There’s around 50 of them currently, so they don’t cover the entire country (but between the GP, pharmacy and VC sites the whole country is very almost covered).
You can find your NHS number here.
Good luck to everyone booking!