As a teacher, I’d prepare to have a good 6 hours’ work at weekends- variable depending on age and stage you teach. In mainstream I taught languages initially and for the first year or two I regularly worked 14 hour days trying to be well prepared. I stopped planning my own things like visiting friends during term time because I was so tired, and needed Sunday afternoons at home getting myself ready for Monday. The Sunday evening dread was real. That was pre kids for me, I wasn’t even 30 when I started.
Then I switched to post-16 social sciences and found the teaching more enjoyable and the planning more engaging although still time-heavy, as there was a lot of reading and watching to find current resources to make the lessons engaging. I was part time by then as I had my dc.
Maths may be lighter on the prep and marking.
The record keeping and bureaucratic micromanagement is next level. Marking schemes, feedback schemes, questioning policies (ie how to question the students)… I had to make explicit how I was teaching literacy and numeracy in MFL, and as a maths teacher so might you (🤔). Extra training, duties, meetings, inspections, learning walks. Your work is constantly scrutinised and judged.
Holidays are great when you have kids, yes, but term time hours are not family friendly, at all. You will struggle to get to your own kids’ parents evenings, plays, sports events. On your school’s open evenings and parents’ evenings you won’t see your kids- you’ll be out before they get up and back home after they’re in bed. As I mentioned, weekends are also working days and rest days. You live from holiday to holiday.
i would recommend spending a fortnight getting some work experience in a school before you decide to go for it. And possibly exploring other options for retraining. For example, adult education- with maths you could go for functional skills and work in community college, prison, etc. lots of options really.