I haven't read the full thread, but DS is hoping to do Maths, Physics and History or Geography at college.
He is well aware that he needs to do work over the summer considering the subjects he's doing.
The teachers will do some sessions through June but after that they are on their own. And so it should be, he knows he can't have 3 months of no maths and walk into an A Level class. If he doesn't do anything, that's on him, not the teachers.
Many of DS's have gone above and beyond and even if something was offered, I'd refuse... They need a bloody break.