Head's fine thanks Skout! Gotta really have a skinful to get a hangover!
I could've used tissue paper OSS, in fact I did on one bit that was really playing hard to get, but what with trying to insert the round bits into the gusset bit and fighting with the bag stiffener which had a strange attraction to the presser foot lever and kept pinging up the presser foot, I just didn't have enough hands, in spite of the Wonder Clips.
Re the fusing problems - someone on another forum said if I'd had the iron at 300F ( I don't think that's very hot in C and certainly not enough to produce steam) then I wouldn't have had a problem - well that's quite probable but then the glue wouldn't have worked either. It's not the cork that reacts- it's the backing fabric that melts and curls up.
I used the bag this morning and it was fine, strap just long enough, and it is roomy enough for specs case, wallet, phone, bunch of keys and a few other essentials - the stuff that always falls to the bottom.