Actually the more I read your reply, the more feeble it sounds.
Chairs and desks can't be moved? Wow.
We've had three months now for the local authorities to get together with teachers/teaching unions to get this sorted.
Even if the kids aren't taught the full curriculum it would mean...
How about teaching them in any of the thousands of currently unused Village Halls, Leisure Centres, Community Buildings?
Maybe even football, rugby and cricket stadiums almost all of which have Corporate Lounges which are large enough and suitable for groups of kids.