Hi. I HEd my son from age 10 right through to IGCSEs. He has autism and adhd, couldn't cope with school and he got no support. At home, we spent a couple of years finding his comfort zone and helping him to settle, then started out on IGCSE work.
We used Pearson/Edexcel resources for most subjects (apart from CIE for Computer Science). I used students from our local RG uni as tutors, which worked very well because they were young and groovy and he was happy to engage with them. They were also very cheap, not embedded in NC, and keen to get some experience for their CVs. He also used Catherine Mooney for English Language but in conjunction with his tutor who worked with him to make sure he could work fully independently before setting him to the assignment tasks - this meant he needed no real guidance from CM because he already knew what he was doing by the time he submitted his work to her.
The most productive tool was past papers, which he did loads of, and went back over his gaps (either alone or with his tutors) to work out where he'd gone wrong.
It also helped to have a good exam centre, experienced in taking external candidates, and in particular home educated teens. We worked with the SENCo, JCQ and the exam boards to get the appropriate access arrangements in place, and that made a big difference.
He took eight subjects and got 7 A*s (Maths, English Language, Chemistry, Physics, Biology, History and Computer Science) and a B (Business studies) and is now in sixth form college doing A levels. He has an EHCP to ensure good support.
HTH.