There is no government medical cannabis card in the UK. You must consult a...

https://wiki-planet.win/index.php/Demystifying_the_UK_Medical_Cannabis_Pathway:_A_Plain-English_Guide_for_Families

There is no government medical cannabis card in the UK. You must consult a specialist who reviews your medical records for a prescription. If prescribed, your use is lawful. Many carry an optional ID card as simple proof of their legal prescription.