There is no official UK government medical cannabis card. Access relies on a...

https://wiki-byte.win/index.php/Is_a_Medical_Cannabis_Card_Mandatory_in_the_UK%3F_A_Guide_to_Legal_Access

There is no official UK government medical cannabis card. Access relies on a specialist consultation and private prescription, based on your medical records. While optional, many patients carry a card as proof of lawful use to help verify their medicine.