How about using buildings to temporarily house school children? Yes many schools are too small to accommodate the number of children needing to be there but why not look at libraries, church halls or other public buildings?
That's being done, at least in several areas I know of.
The problem is that buildings like churches would need to be paid for and schools don't have the budget. Other buildings like community halls and libraries are also being sought after by multiple schools.
We have two primary schools and a large high school here. It's not just as simple as DS and DD's HT cherry-picking all the buildings she wants to use. There's got to be prioritising done. Plus some of those buildings are already being used for things like food parcel deliveries or don't meet the safety standards.
There's a guy locally who keeps banging on about how the schools just need to hire portacabins as the high school has done that while the new building was being built. He cannot seem to grasp that a few schools using portakabin classrooms as a temporary measure doesn't mean there are enough portakabin classrooms around to put several into the playground of every single school in the UK.
Stupidly we have an easy fix locally (new high school building is ready, old school building is still standing and in use, yet is still scheduled to be demolished in the summer holidays) that is being discounted and that is extremely frustrating to staff and parents alike.