Teen & Tween - the govt. also pretty much insists that every teacher in every school does every single thing themselves. I haven't taught in the UK since 2008 and I know it's got worse, but even back then, there would be things we HAD to do - like get sent out examples of work. Each teacher had to grade & annotate according to certain criteria. Then hand in what they'd done to the HOD, then have a meeting to discuss the grades. Then the HOD had to submit the grades, then the school got checked up on etc.
If there are new teachers, or a new exam then there has to be a pre-meeting to go over that stuff even before anyone reads the material and does the grading. A fairly conservative estimate is about 10 hours per teacher to complete the full process. That is for ONE change in syllabus/exam etc, and each teacher could be teaching at KS3, KS4 (maybe 2 subjects) and KS5 (again, possibly 2 subjects).
If a school doesn't do this and document it properly, then (worst case scenario) they could face having ALL of their GCSE and A Level results pulled down a grade, or even be banned from entering students for exams.
That's just one small part of what goes on.
To those saying that we should just try to tell ourselves that that we get 5 weeks of holiday - whenever pay is brought up, teachers are told by gov. that we effectively earn more than we do, but it is pro-rata-ed down because of the extra holidays. If we were paid comparable amounts for the levels of education, training and responsibility that we hold, then no gov. could afford to run schools. So, we're told to accept lower pay because we get more holidays. Then we're told to work through those holidays.
I currently live in the US, but whenever I think about returning to the UK, I say there's no way I'll return to teaching there. And I'm a 'tough cookie' in the teaching world, who often advised trainees to think carefully if they weren't up to the challenge.