No government medical cannabis card exists. You need a private prescription...

https://www.herald-dispatch.com/sponsored/how-to-get-a-medical-cannabis-card-in-the-uk-step-by-step/article_a7f9fcb2-55db-40ff-857f-db6b98c92a97.html

No government medical cannabis card exists. You need a private prescription after a specialist consultation and medical record review. You may carry an optional card as proof of lawful use, but your valid prescription is the essential legal document.