There is no government medical cannabis card. You must first see a specialist...

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

There is no government medical cannabis card. You must first see a specialist who reviews your medical records for a prescription. Once prescribed, an optional card serves as proof of lawful use for the police or public