Since 2018, UK cannabis law has changed under the Misuse of Drugs Regulations...

https://dlf-ne.org/what-international-treaties-affect-uk-cannabis-law/

Since 2018, UK cannabis law has changed under the Misuse of Drugs Regulations 2001, not the Misuse of Drugs Act 1971. Specialist doctors can now prescribe some cannabis-based medicines, like Sativex and Epidyolex, which are licensed for medical use