Where there are variations by which age people can get booked, it's often to do with if they are booking via local GP led system or national booking system. Lots of people don't realise there are 2 systems running in parallel.
The National Booking System via the NHS booking site has nationwide age and other criteria for booking. It seems to be allowing 44s or possibly even 43s to book and those under 45 who are now eligible were being added yesterday. At some point today the first page will probabbly update to show the accurate ages who can now book. No personal invitation is needed to use the site and it will only let you book if eligible so people don't need to worry about being queue jumpers. The site books people into the sites run by the NHS which are often larger vaccination centres or can be hospital hubs occasionally or pharmacies. People book both appointments at once. Often people will have to travel a bit but for most this will be first place they can book a vaccine and the fastest way to be jabbed.
GP led services run parallel. They use a different booking system and people will get a text or call inviting them to book. This is where differences in criteria such as age occur with some moving ahead...often due to demographic differences in areas or variation in uptake meaning some have more supply to offer to younger people now. The GP led services are more numerous but smaller in capacity than the larger NHS centres. They are often in community centres of Church halls but some are in surgeries and one GP led vaccine centre will often serve several local GP surgeries. Often appointments for 1st jabs are offered with very short notice at the moment as in the weeks of 12 and 19 April, GPs had zero new deliveries for 1st jabs. That means they are using up supply they already had or that is left over after giving the required 2nd jabs. That is why most 1st jab peoole are going to mass centres as that's where most of the limited supply for 1st jabs currently is. That might change but may well not,mespeciallybearlespecially lots of GPs pull out from being involved in the 2nd phases of jabbing...just due to their normal workload taking their time. GP led services also pick up anyone eligible who doesn't book on the national system....sometimes offering within a day or 2 and sometimes not for several weeks, depending on supply. So those who can't or won't travel will get offered a more local jab, but they often have to wait a bit longer for it.
So when people under 44 especially say they have been jabbed or booked, it would really help others trying to see where they are in the queu, if they said if they had a GP invite and if they were jabbed at a local centre. Everyone in MN waiting has no control over where they live and what GPs in other areas are doing. What's happening with the National Booking Service is what should be able to impact everyone.