Thank you everyone for your kind words, advice and encouragement.
We've visited colleges several times and its been very confusing. Sigh.
He couldn't get onto A'Levels anywhere, but it was suggested he could do an Access course. (They were wrong) There was a lot of confusion over the functional skills - were they GCSE equivalent like some said, or not. I now appreciate for him they were largely a meaningless waste of time, but hey. 
He has now signed up to a Level 2 Btec course - with a GCSE maths and English element with a view to doing an Access course next year.
I think this is fair and it works in that it'll be a gradual re-introduction into full-time education, its modular, and he can get his GCSE's etc. The downside is that he genuinely didn't fancy any of the Btecs on offer. He hopes to do a degree in Psychology - this might change - but the best they could do was a Btec in sciences (which he has GCSe's) or animal science or social or health care.
He eventually decided on [bites nails] public service, not because he wants to be a copper, but because it seems an interesting all-round course with fitness, law, crime, workplace stuff.
If anyone knows about the Btec in Public Service, do let me know!
Thank you again. It's been very frustrating and exasperating. I know I am over-involved - a product of the 'depression years' - and would really like to take a step-back but feel I can't yet.
Sigh. Hopefully this will work out!