I assume you are willing to accept a very substantial pay cut so I’ll try and keep it to the actual job itself.
I was a teacher, and it’s a very draining job. If you’re introverted you are likely to struggle - if you’re feeling a bit ill, or maybe having a bad day you can’t just sit behind a laptop and do a few meetings, obviously no working from home, you have to be “on” performing, happy; engaged with 100+ children/teens over the day. Yes the hours are draining and long, you’ll get hardly any breaks in the day and if your school doesn’t have a proper behaviour policy you’ll feel unsupported and stressed constantly.
There’s no sick days (you obviously can’t work if you’re horrendously ill but management hate having to pay for supply so you’ll be working when maybe in an office job you’d take a sick day or wfh/leave early). And obviously no flexibility on holidays and things like being able to pop to the shop at lunch. Some schools will expect you to give up time during Easter and May holidays to support gcse revision (unpaid).
In some schools teachers may share resources and lesson plans but otherwise you’re on your own. At least with maths after a year or two you should be able to reuse your own lessons with some tweaks.
You probably know all the above already but the other things I’d add are schools can be a very cliquey place to work and if you don’t get on with your colleagues (if you’re a maths teacher the other maths dept) then prepared to feel isolated at work. The flip side is if you do get on with them you’ll have a supportive team that will make a huge positive difference to your day to day.
perhaps if you’re changing careers you’ll have more resilience and be better able to manage the workload, hours and expectations. So I’d really think about whether you feel you are the type of person that gets energy from others and would love interacting with close to 200 children a day (very possible if you have 5 classes of 30 plus a form/tutor group plus all the kids you’ll see on break duty etc). The school you choose to work in will be critical - and I don’t just mean “good” (results) but the point around having a supportive team, realistic expectations on what a good lesson looks like, whether there is a supportive behaviour policy. Are there proper consequences for children who distract, swear or get violent with other pupils or staff? You want to spend time teaching not doing behaviour management.
What are the book marking and homework requirements (ie when you look for a job think about all the “extra” things you might have to do - you want to work in a school that makes things easier, for example setting homework online via a portal so then things are automatically marked and checked etc rather than you setting, marking and logging homework outside of lesson time). Will you have to run an afterschool club and what are the break/lunch duty requirements?
I don’t want to put you off as it can be a really rewarding job and give you some real highs. But the constant grind and exhaustion (I felt I never could really enjoy Sunday afternoons, and felt too tired most evenings to have plans) just wasn’t for me. But some colleagues had seemed to find it much easier got their energy from it. I think it comes down to the individual personality and the school dynamic. Good luck if you do go for it.