Your advice about keeping flying is, I'm sure, very sound indeed Ramshorn. Whatever my course of action I'll endeavour to maintain flying currency, even if doing so results in nothing more than me having a good time. As far as my decision about instructing goes I suspect it might all come down to whether or not I could realistically expect to get a reasonable amount of work. If I could only pick up an hour or so per week in the medium term then I'd have to question the worth.
I should probably try to get a better understanding of the instruction market at this point!
Thanks for posting.