Is there a way of adding a form of authentication to WDS after the F12 keypress but before the WDS unattend.xml takes place?

We've left most of our machines on the same boot order as when they were imaged as none of the students have the ability to shutdown, restart or power on machines physically or remotely, so it works out easier for us when we come to image the machines next time around.......

Problem is if one BSODs and restarts itself and a kid is sat infront, the merrily press F12 and the next thing we know the PC needs to run throughthe whole image process >_<