Just wanted to report on my successful vaccine sign up. I have no DNI so entered my passport number, I received confirmation by email straight after, then another a few hours later on Sunday night asking me to book the appointment and that it was open for 48hrs. I could only choose Tuesday 29th (2 days later) and some places weren't available. I had email confirmation of my appointment straight after. Also, as I'm here on an expired visa from a couple of years ago, I checked with a friend who is a hospital Dr to see if I was eligible without a DNI as I had assumed I wouldn't be or at least a low priority. He said you just need a 'service agreement/bill' of some sort to show you live here and are not a visiting tourist. I'm going to take my apartment contract. It does say as much on the signup website as well - DNI or service agreement showing name. My experience so far has been excellent, all done within minutes. I'll post an update how it goes as still a little nervous as I may be met by someone at the entrance who misunderstands the technicalities and insists on a DNI. Fingers crossed.
ps. Forgot to say website said it is open to over 40 year olds.