The only legal form of CBD oil is as a component of products that are registered as ‘Novel Foods’. CBD oil cannot be sold as medicine in the UK. Any CBD oil that you purchase must have less than 1% THC content to be legal (THC is the main psychoactive component in Cannabis).
I’ve never taken CBD but as a chronic pain sufferer and therefore an intermittent sleeper I can understand your interest Jojoe.
Can I ask any responders on this thread not to link or encourage posters to consider any substance that is prohibited in the UK. Thank you.