I'm sorry you've had a bit of a hard time on here, OP. I don't disagree with much of what has been said, however, I have worked with plenty of teachers who have made a successful transfer from industry or corporate jobs into teaching (I'm one, although I was freelancing when I career changed and not earning that much, which made the transition less painful - there weren't any bursaries when I trained as it was the year of the coalition govt when they suspended them all). I don't think you should give up on this idea before checking it out fully and spending some time in schools.
I just wanted to say three things really. Firstly, you would have more luck finding the sort of post you seek in a grammar/independent/any large school with a strong science dept and plenty of students looking to study STEM or medicine. An ex-industry chemist I worked with made himself very useful advising would-be medicine applicants and running the science department. He had good management skills, which his staff appreciated (there are not that many trained managers in schools!) This was at a grammar and there were points on the salary scale for industry and other relevant experience.
Secondly, you are aware that you don't need to be a qualified teacher to try teaching for a year to see if you like it? You just need to find a school that'll take you on. That's what I did and then I trained on the job. You wouldn't get a bursary, of course, but you would get paid. I got paid a little extra based on experience outside teaching but relevant to the subject. It definitely helped that they couldn't recruit for my subject...
Thirdly, you need to play the long game. Perhaps the first few years you'd have to teach a lot of Biology, or whatever. Maybe you'd have random bits of KS3 Geography on your timetable to begin with. Maybe you'd have to move schools a few times to find the right fit. But it is possible to negotiate. In all the schools I've worked in, it was worth cultivating the person who did the timetabling and Heads of Dept in subjects one would consider teaching as a second subject. There are generally more or less palatable options e.g. I was very reluctant to take on a Maths timetable (I'm an Economics specialist) so I made myself useful to the History department instead.
Money is tight, but lots of students want to do Chemistry A level. Schools have got to square that circle somehow.
Finally - yes it is hard when you have young children, but not impossible. I haven't got time to read back through the thread (lessons to plan!) but a lot will hinge on whether you have a supportive partner and/or excellent childcare. I found it worthwhile to pay for childcare for some of the school holidays when I was starting out so I could get ahead. I don't know how people manage who only have term time childcare or whose partners don't support their efforts.
Good luck. Don't write it off without doing some research. Every school is individual and the people who run them are different too. You only need to find one school that suits you and you them.
I also wanted to say that I have had so much help over the years from friends/acquaintances/random colleagues I've met at conferences or online, up to and including sharing entire schemes of work. I also had a terrific mentor in my first year and that has got to be a big part of why I made a successful transition. One thing I have really liked over the last 8 years is the feeling that I was joining a big family of people doing the same thing. I didn't feel that in previous careers.
Anyway, I hope that gives a little balance.