I was asked for an update so here goes..........
I saw my GP last Friday and asked his opinion re flying. His reply was that as I had managed to reduce the level of Tramadol significantly he didn't see a problem.
I had a flight with a very experienced instructor today and he was quite happy with my flying. I rent aircraft from the company he part owns.
Please bear in mind that I fly on an NPPL and according to the LAA it's virtually up to me if I fly with regard to medical issues! However, I would certainly NOT fly if I didn't feel up to it.
I also fly with a flying partner and we monitor each other very closely, taking over the workload from each other when necessary.
I would like to thank all the people who have contributed to my question in such a positive manner.