We've had lice here too and it was a huge PITA for me. I actually got them myself and have long, thick hair and was very tempted to cut it all off. I dread the next time I find a lice.
Our school board has a policy that if a teacher notices lice on a child they contact the parents but do not send the child home early. The rationale being that by the time there are enough lice/nits on a kid to notice, they've likely had them for a couple weeks so what's a few more hours. The child must be treated with an anti-lice shampoo and then can return to school 24 hours later if they are nit free.