There’s no official UK government cannabis card. Access is prescription-first...

https://mighty-wiki.win/index.php/Is_medical_cannabis_delivered_to_your_home_in_the_UK_or_do_you_pick_it_up%3F

There’s no official UK government cannabis card. Access is prescription-first via a specialist consultant after reviewing your medical records. If prescribed, you can opt for a private clinic card as optional proof of lawful use for police or employers.