I can't speak for rogerd of course, but when I was at school we had this kid in the class who was constantly ill (or constantly away anyway). He used to turn up to a class maybe once or twice a month.
Rest of the time he was at home, getting personal one-to-one tuition.
He managed to get all his exams, and to all intents and purposes he learned the same stuff that all the rest of us did. But it never felt to us like he was part of the class.