Since cannabis was rescheduled in 2018, NHS prescribing is technically allowed...

https://highstylife.com/how-do-i-find-a-legit-medical-cannabis-clinic-in-the-uk/

Since cannabis was rescheduled in 2018, NHS prescribing is technically allowed but remains rare, limited to specialist doctors and only for a few conditions—like nabilone for nausea, MS spasticity spray trials