Ouch! I’m not in the UK, so I didn’t follow it too closely, but they had some problem with the NHS recently, though it seemed that they got it under control. Maybe that is not the case though. In that case, hrt.cafe says that the following homebrewers also sell to the UK
- voixceleste
- astrovials
- silvermaplelabs
- teahrt
- Otokono Pharmaceuticals (old and trusted, but suffering massive shipping delays due to immense load, last time I checked)
You probably want Estradiol Enanthate which has to be injected weekly. I’d recommend to get a multi-year supply just to be on the safe side. With injections monotherapy is viable! Most people seem to calculate one vial lasting for about one year, give or take depending on your exact dosing.
There is also the option to buy raw estradiol and mix your own spray or gel. The advantage is that a lifetime-supply of E is comparatively affordable this way. Check /r/estrogel on reddit for more info on that.
To add to this: The usual joke on /r/transDIY whenever someone manages to miscalculate and do a 10× overdose is “congrats, you are pregnant now”, because E-levels during pregnancy are crazy high. And you don’t exactly see pregnant women dying left and right either, so don’t worry too much.