Medical cannabis has been legal since 2018, but it remains strictly controlled....

https://angelowlnv711.yousher.com/can-my-gp-prescribe-medical-cannabis-in-the-uk-a-guide-to-navigating-the-rules

Medical cannabis has been legal since 2018, but it remains strictly controlled. You cannot get a prescription from a GP; it requires a specialist consultant, typically after other treatments have failed