Thank you for your replies. I have now been able to correct the cable adjustment myself.
I think I must have had brain fade when I started this topic as the answer to getting access to the clutch cable top nut at the engine end, was very easily solved by fully loosening off the cable at the clutch lever and then pushing the cable sheath out of the engine end bracket, which allowed fully and easy access to the top adjusting nut.
A simple task made impossibly confusing by my brain fade. 🤪