thislittlekitty you are correct, nursery is not compulsory, the general consensus and pressure to send a dc to a nursery is ridiculous. He's not in or been in complete isolation, he has 3 other siblings, so 3 under school age would be same ratios as a childminder would have during the school day.
You've said ds is yr1, so whether you sent to nursery or not is irrelevant now, he's been in school for over a year.
I would be asking the school what they are trying to prevent or distract from this behaviour, if he's bored why is he bored, if it's when he's unsupervised why is he being left unsupervised, what is triggering these behaviours?
Does he display the behaviours at home? If he doesn't what is different at school that means he does there, if he does how do you manage them and does it work? Also how does the school manage it, could he be doing it for attention?
Does he eat paper at home? Eating non food items is called pica, can be an indicator or SN but more often can be an indicator of vitamin or mineral deficiency, so a good multi vitamin with iron could help if you don't already give him one.