Not a single CBD product legally available in the UK is FSA approved. I'm not aware of any clinical trials having been completed on them in the UK and they're unlikely to do so because they're classed as food supplements not medicine's.
The doses are so low of what's legally available that in my opinion they're unlikely to be any more than a placebo, particularly if you're in a significant degree or pain and suffering which I'm sorry to hear.
The reviews/results are to my knowledge only anecdotal opinion's of users or as you alluded to in your original post those who are praising it as they're selling it or being paid to endorse it.
Of course there's lots of celebrities who have and are endorsing it. If I was offered the money they are to do so then I probably would too.
With a minimal amount of looking into it you'll be able to find a plethora of people saying it didn't work at all for them and it had no effect other than leaving them feeling worse due to being heavily out of pocket.
I've known people who were terminally ill who were able to get CBD oil of higher strength through non legal measures which I know helped them greatly with pain but it was much stronger doseage than the maximum 0.2% permitted legally.
I'm definitely not suggesting or advising you do the same, I'm only mentioning that as a point of reference to help with the distinction between the pain relief offered by CBD oil and the likelihood of you experiencing that through highly priced commercially available products because I don't want you wasting your money.