SallyB392 so sorry your GS isn't happy at school it doesn't suit everyone. I wonder about taking 1 day and would it be better to take a couple of afternoons off, or even 3. Literacy and numeracy are usually done in the morning so that might be less disruptive. There are children who even at 7 find a whole day too long, knowing they finish at lunchtime really helps. You need to discuss all the options with his school.
My friend's daughter was obsessed with wildlife problems when she was younger it helped her to feel she was doing something about it. Perhaps your GS could fundraise for something he feels worried about.
To take it forward his mum needs to raise the matter with the class teacher and then the head teacher. She should then ask for a meeting with the CT HT and whoever is special needs support. If she has evidence of his autism, a letter of support from her GP or any other thing she considers relevant she should take it with her. Hopefully they will agree something. If she has problems she may need to take things further and ask for a proper assesment of him by an educational psychologist. Hope things work out.
How do you acknowledge Easter.