Thanks for this - I think my GP quite enjoys me going in and arguing about things! We agreed I could continue if I wished - I said I'd go on lower strength (0.625 instead of 1.25), she gave me a print-out from Patient UK, I said I'd do some more research on trials and ages, so we'll see how it goes!
I was on thyroid until recently, which she wanted me to stop, but I'm not arguing with that unless I get symptoms again.