There is no official UK government cannabis card. Access requires a specialist...

https://oscar-wiki.win/index.php/What_is_the_Difference_Between_a_Cannabis_Prescription_and_a_Cannabis_Card_in_the_UK%3F

There is no official UK government cannabis card. Access requires a specialist consultation and a review of your medical records for a prescription. Once prescribed, an optional patient card serves as useful proof of your lawful treatment to others.