I am a teacher. Luckily, I do supply teaching now, as full time teaching is incredibly tough. The behaviour seen here is quite mild and it seems like quite a well run school. In some schools, there is fighting, children jumping on tables, children hurting others, children roaming the corridors, swearing, carrying knives, drugs, AI used to film teachers and lots more. There is a teacher shortage for a reason. It's very, very tough.
And it's not just about dealing with behaviour. What is not coming across in the tv series, is the crazy pressure put on teachers for the children to achieve. If the anxious child who doesn't like tests get a poor grade, similarly the child who has a very difficult home life, and if there a few like that in the class, ofsted will be in demanding answers for the low percentage of high grades- No excuses they say. Schools are then graded as outstanding, good, requires improvement etc accordingly, but it's so difficult with difficult classes.
Then the workload. It's not just marking. Teachers can spend hours trying to find ways to help so many of the divers characters and finding the resources. Phone calls to parents, forms to complete etc.