I was a secondary maths teacher for 14 years before I swapped to work for the LA.
In my experience working part time 2-3 days a week and it’s manageable. By doing this you have less planning and marking and so I could keep my weekends free for my own children.
Working full time would require at least a 50 hour week, sometimes more. I would be in school for 7:30am and not leave until after 5pm. Sort dinner and then get the laptop out again to plan lessons for another few hours. Sundays would be for marking.
Workload can vary hugely between schools with different planning and marking policies. However the pressure to get results from kids (especially in maths) is intense. You desperately need the kids to do well, but often they don’t give a shit and won’t listen to anything you say. Won’t do class work, you spend hours after school supervising them in detentions because they won’t do homework.
I was swore at, pushed, had things thrown at me. On the flip side there are obviously some great kids too!
You couldn’t pay me enough to go back into a classroom now.
My best advice is to shadow a teacher for at least a week. And while doing so remember they have experience and preplanned lessons that make it easier for them. Imagine doing the job having to plan everything from scratch and having no prebuilt relationships with the kids.