Supernana1 Look up The Pernicious Anaemia Society. There are on-line support groups with lots of tips and advice.
For many years I have "Self Injected" as 12 weekly is no use to me. I order my B12 from Amazon Germany, it costs pennies.
To put things in context, in some counties you can buy and injection at the Chemists for a very reasonable price, so why not here in the UK?
In the UK you can get B12 injections at Beauty Salons at whatever they want to charge. Near where I live the Salon currently charges £24 per injection.
Also in some countries there isn't the fight to get more frequent injections. When I worked abroad my Dr had me on 4 weekly injections, no fuss but back in the UK it was 12 weekly.
I've needed injections for 25 years +. During lockdown my Dr stopped my injections and wanted to put me on tablets. Ha Ha. Tablets don't work for lots of people, me included.
I don't have "Intrinsic Factor" or simply put the bridge between my gut and blood stream so tablets are of no use at all to me.
I hope you find some useful information and ways to help manage your situation as it's not easy.