Bloody Hell. I only went off to make Beetroot Soup whilst Mr D was snoring in front of watching the Tour de France.
Birds like chickens lay clutches of eggs. The wild originator of Domestic Chickens, the Guinea Fowl, will lay an egg a day and will lay around 80-160 eggs in a season in around 4 batches of 30 with a short gap in between, usually from around March to September. The difference is that domestic chickens have been bred to lay over a longer season and the difference in a controlled environment (apart from the expressly horrible ones) is that the light levels are manipulated so that they don't go off lay in response to the shorter daylight.
SB would be fine if she just shut the duck up about the eleven plus. If she wasn't saying he might not be with his friends and haranguing him about what the stakes are, he'd be fine. Oh, and if she wasn't being a screaming, howling absolute state, going batshit over his books, getting half dead kittens, announcing she was never going home from Scotland, going through a number of parental figures and generally being an absolute liability and headfuck as a parent by her own account, he probably wouldn't be anywhere near as anxious about life.
The school will be planning how to support the kids when they're back. The DSL will probably have been keeping an eye on her SM for a start, so s/he knows the absolute batshittery the child has been subjected to over lockdown. In an 11+ area, they're well used to the stresses and will be taking the extra ones, both external and those from parents/family into account for ALL children. In addition to the usual stuff he gets, she's also been hassling him about the eleven plus. Just leave the kid the duck alone. Let his Dad and Stepmum handle it. Reckon they're saying he'll be fine wherever he goes and not to worry about it.
In short, JUST duck OFF.