A Around a third of new teachers don't start their careers in teaching until they are aged over 30. Most, like you, will have had well-paying jobs in different professions. All acknowledge that transferring to teaching may mean some financial sacrifice. It is perfectly legitimate for a school to take account of your previous experience when calculating your starting salary, and your friends may be correct that M3 is a sensible place to start, especially as you will be teaching in a shortage subject.
However, you still have to consider the risks associated with your change of career. Although you will expect your training fees to be paid, you will still have to support yourself during the nine months of the PGCE course and then there is the risk associated with finding a teaching post; in your case, I expect this will be no problem, but you cannot be sure. I suggest that you make sure you have not just the academic qualities needed to be a teacher, but the personal qualities to cope with the day to day demands of working in a secondary school. I assume that you have already spent some time in schools understanding the role of the teacher. If you haven't, then you should try to do so before any interview.
As you already have a career goal in mind, you will need to plan your early career carefully. As a maths teacher, you would expect to have five steps on the ladder to headship. Along the way you will also need to acquire the NPQH (National Professional Qualification for Headship) and probably some further study at an earlier stage. However, there are other posts that might come to seem more attractive than headship, so do keep an open mind and be flexible John Howson is a recruitment analyst and visiting professor of education at Oxford Brookes university. To ask him a question, email him at email@example.com