You can’t take exams at two different centres in the same ‘series’ (. summer or January). If the timetable permits, you could ask the school to enter you for extra exams, though you might have to pay. Ask your exams officer – they’re the experts and know you son’s situation.
It looks like you’ve read the page on science GCSEs ( http:///science-gcse/ ) so you know the structure. Because of the new flexibility that I describe on that page, the school can organise science in different ways. There are only three exams for triple science. They can be taken together in year 11, or split between yr 10 and 11. Biology in year 10 and the others in yr 11. Or, the school could go down the route of Core science in yr10 and additional plus further addition in year 11.
Thanks very much for all your comments - they have been very helpful. DS1 is getting down to some work and attending his schools holiday revision classes. He sets himself tasks for each day - but won't make out a timetable. This is fine, although I pushed for him to do some work on the subjects he hates first, helped him with it and he seems relieved that he's made a start there. His teachers have asked for pieces of work and test questions to be handed in - he seems to appreciate a bit of help and a push to get these done. It is still tortuous, but he is working and I'm happy this is constructive and he's not sitting there overwhelmed by it all as I think he was a few weeks ago (hence the anger and general denial - small chunks and help with the subjects he'd rather ignore has helped I think)
....we'll carry on....thanks again!