Typical day as primary school teacher:
7:30 arrive, review x5-6 lessons for the day, trim worksheets to be stuck in books (30 or more pieces of paper), check/reply to emails
8:30 set up morning work, hand out books for first lesson
8:45-10:30 - teach, mark a little in class but can't do much else.
10:30-10:45 children's break, either on duty or mad dash to the loo and tidying classroom/setting up next lesson
10:45-12:30 - teaching
12:30 - 1:30 - lunch. Scoff some food, inevitably get pulled out to deal with behaviour, tidy classroom, set up for next lessons. Log safeguarding.
1:30-3:15 teaching
3:15 - 3:30 - dismiss class, catch up with parents
3:30 - 5:00 - marking appx 150 books, can take 1-2 mins per book minimum. Log behaviour/safeguarding incidents. Phone parents. Finalise a few resources for children with specific additional needs for next days lessons. Review planning based on marking. Tidy classroom.
Some days none of that after school work can be done if there is a staff meeting. Some days there is 2 hrs PPA which can either be used to do some planning or marking but also gets used to deal with behaviour if the class aren't behaving for whoever is covering.
Planning a lesson generally takes as long as the lessons x2 in the early days of teaching but gets much quicker with practise. I'd say for an English lesson it would take me 45 mins - an hour to plan and find or make good resources. Lots of schools buy in planning from companies these days but there's often a lot of prep to do still along with making sure all children with different needs can access.
I'd use holidays to get ahead with planning and try to do the following 6 weeks' planning and making resources. But planning has to be adapted by how the children respond so it can only ever be loosely planned that far ahead so needs to be worked on throughout the term.
On top of the daily work there's things like:
EHCP reviews
Additional meetings with head/senco/parents
Writing SEN/LAC/EAL reports
Writing end of year/mid year reports
Preparing class assemblies
Parents evenings
There are so many behaviour and safeguarding issues in schools these days and they all need reporting and following up
Recording assessment data on whatever database SLT chooses
Updating displays
All of this is for a standard teacher with no additional responsibility. Most teachers also lead a subject or an area such as school council which is an additional workload that usually doesn't come with extra time although some school timetable half a day every 6 weeks for subject leaders.
I've left teaching and been working in another field for a year. I'm not senior but the workload is incomparable. I actually work in education at the moment in an admin role. My manager is constantly complaining about school staff being too busy to do the things she asks them to do and huffs that she is also busy. I just smile and nod as she's got no idea what it's like working in a school. It's constant fire fighting, everything that lands on your desk is urgent and important. Loads of fun but highly stressful!