It's not a teacher's job to 'stamp out crap behaviour.' It's a teacher's job to manage the behaviour in the classroom, so that there is a learning environment that works.
It's interesting to note the juxtaposition between this thread and those bemoaning the state of their houses at the end of the holiday, desperate for the children to be back at school, challenging uniform rules, etc etc.
I think that it's not unreasonable to have an emergency contact who can get to the school quickly, unless there are totally unforeseen circumstances. I think an hour is probably OK, but I've seen really unwell children suffering for several hours because no one is available to collect them. Then the school has to make a judgement about the severity of the illness.
And feesh you may have been paid to deal with obnoxious people as part of your HR role. Teachers are paid to teach children, to plan lessons, to provide data, to review and evaluate their teaching and the progress of their pupils, A young teacher will not be earning £30k. They will also be taking work home, planning lessons, entering data, working early mornings and late nights. I've been screamed at, physically attacked, verbally abused and I wasn't paid to have to deal with that.