I don't want British building code rules and
stuff, just ideas about sheds for school rooms for people who have
walked 10 miles and have no money for food let alone equipment.

I'm sorry if this is an unhelpful comment but building regulations do
exist in places such as Uganda, Ethiopia and Rwanda. The level of
compliance may not be as high as here (let alone as in Germany,
Switzerland etc). But some (many?) NGOs may wish to comply with the
local codes - especially for schools.
--
Robin
PM may be sent to rbw0{at}hotmail{dot}com