My secondary school didn't impose a uniform on us at first... It all changed when we got a new headmaster though.
I would usually beat the heat in summer with the blazer in my bag and shirt untucked. Noone but the head cared about this and he implied that having my shirt left out like that meant I wanted to spend the break picking up litter. I managed to talk my way out of it and after that I don't think he cared.
If you aren't allowed to do that just freeze a few bottles of water & take them with you. Keep them in separate compartments or they'll destroy your books etc.
I would usually beat the heat in summer with the blazer in my bag and shirt untucked. Noone but the head cared about this and he implied that having my shirt left out like that meant I wanted to spend the break picking up litter. I managed to talk my way out of it and after that I don't think he cared.
If you aren't allowed to do that just freeze a few bottles of water & take them with you. Keep them in separate compartments or they'll destroy your books etc.