I have a y4 with high functioning ASD, dyslexia and dyspraxia. The kind of child who can tell you in detail about strategies and weaponary of WW2 battles, but struggles to write his name legibly and with the letters the right way round. We've had days where it's taken 30 minutes (including two meltdowns) to write the date.
I have the advantage of being a SAHM and a decade of teaching experience, it still isn't easy! Not least because school = teachers and learning and and home = relaxation. DS masks well and puts in a good effort at school even if he's not very productive (no support, very slow writing speed, struggles to multi-task). The problem is I have this nice hazy notion that this is an opportnity to boost his weak basic skills with a 1:2 ratio (also have a y2 child).
I've adapted our rythmns over the last couple of weeks. Some days we have more energy to get more done. Some days are just write-offs from the start.
Get to the key point of the work. If you have a bright child with SNs, don't worry about doing stages 1, 2, 3, 4, 5 & 6. If they can do 5 & 6 without the busy work of 1, 2, 3 & 4 to wear out their attention span.
Make sure there is something that engages them.
Do the tricky bits early in the day, or at their most switched on time.
I'm using some of DS2's y2 work as revision on DS1's weaker areas.
Plan tasks together so it's easier for them to accomplish bigger tasks. Mind maps, highlighters, colours, draft pad to model answers on.
Learning time doesn't have to be consistent blocks. Our blocks get shorter through the day. Lots of little play breaks. A longer mid-morning break and a 2 hour lunch.
If they don't do the work set by school, what exactly will school do about it? Frog march him in for a detention?
School will have a good idea of who will fly through and self study through everything set and half the Encyclopeadia Galactica, who will give it a fair go and who won't even pick up a pencil or a book in the time off. As long as you make a fair effort, you'll do fine.