Yeah I used to pray at school as well.
Did you pray zohar as well?
I prayed zohar at school as well as jamat. Me and some of my friends got together and we prayed. We did wudhu at the changing rooms (they had a shower there as well) and then we prayed in one of the classrooms. The teacher was so nice because she let us pray everytime. I miss school because of the teachers, not the students - most of them were just... I don't know.
But yeah there was my lunchtime done. But we could pray at home in summer because namaz time for zohar was longer. If we prayed jamat at lunchtime it would clash in with midday time (zawal time) which means we couldn't pray so we prayed at home.
I don't know how you could pray jamat though?
We only prayed Fardh, we didn't have enough time to pray Sunnat or Nafl which sucks because I always pray them.