My son is 6 and suffers with anxiety, we got a call from school the other week asking if he could go back and we decided against it due to the non normal settings. Another call this week asking to consider going back a week on Monday for the 2nd phase. After a long conversation with the head and the guarantees she has given us, i.e normal teacher, his cousin and a couple of close friends in the same bubble we are giving it a go but any signs of his anxiety increasing he will be pulled back out.
Tbh he would probably be anxious returning anyway, it's a very unusual situation. But the school.staff will do their best to nake it work because primarily you go into that line of work because you want the best for children.