Purple planet - when children in my class receive additional support, it tends to happen during the related lesson.
Ie. if they need additional support with literacy, and it's something that needs to be done in a quiet place, free from distrations, then it will happen during the literacy lesson. I never expect a child to then cover the work being done in class. What they are doing is a replacement.
How often is your dc receiving support?
I'm not sure what your angle on this is. Are you saying that you would expect your dc to have a chance to catch up with the missed work, or that your dc's school is expecting your dc to cover the work either at home, or during another lesson.
I can't see either of those working to be honest. If your dc has missed something in the lesson, then it would be unreasonable to expect an adult to spend more time one to one out of the classroom re-teaching it. Most things in the curriculum are re-visted several times over the course of a year, if not term. If it was that important, then your dc should not have been taken out during that session.
If you are being asked to cover it at home, then that is unreasonable too. As I said, almost everything in the curriculum is re-visted.
Frecklyspeckly - that sounds very badly handled by the teacher. I would be very surprised if any additional support ate into his free time (I presume you mean playtimes or lunchtimes). There may also not be any extra homework.
Additional literacy interventions should be closely targetted and assessed over a limited timeframe in order to assess their effect on the child's progress and skills. Therefore, unless your dc has a statement, you may find that the additional support happens for only half a term, for a maximum of half an hour a day (very often much less), so the impact in terms of literacy development should be greater than the impact of missing parts of other lessons due to the small group/individual support and tasks specifically targetted at your child's needs.
Sorry, I waffled on. No idea if any of it helps!