I'm part of a tiny programming group at school but there's a problem.
Last year I used Ubuntu on a VM: editing in Gedit, compiling in terminal. This year they've removed Ubuntu from the VM's OSs, making it impossible to edit or compile code (no IDEs installed, and the school won't let you compile anything on Windows). I've tried booting Linux from a USB but it requires an admin password.
Are there any: (a) ways of getting round these restrictions, (b) places online where I can compile and edit code ?
These kinds of problems are often straight from the district -- meaning that someone at some point is going to have to appeal to the school district superintendent in order to get authorization to get the software back.
 Meaning, your school's IT department likely has little to nothing to do with it.
No, pretty much the head of the IT department determines what is allowed to put on the computers and if they deem it malicious in any way they will remove it and block it. I'm guessing someone tried doing something with the Ubuntu on VM and deemed it malicious and blocked it. The IT department head is controlled by the head of the institution too.