Far easier said than done, but I'd seriously recommend using another GP and/or making a formal complaint. GP surgeries have a lot of oversight and "GP won't give you prescribed medicine and loudly complains at you when they do" is a pretty fair complaint. You have a right to dignified and discreet healthcare from the NHS. Changing GP is typically easy if there are others around, but otherwise, formally complain to the surgery, then escalate that complaint to the local health authority if they don't resolve it.
I've had to do it for being deliberately misled about my drugs before, and it was swiftly acted upon. I sent one email, and they publicly logged a change in internal procedure a week later.
Waiting for seeders is definitely a thing, I once waited 8 months for a seeder to show up (and they did!)