I remember career changing to maths teaching 10 years ago in my mid 40's and everyone saying (with a wry smile) I must be mad. Perhaps you've heard this already. I don't think anyone has yet commented that the emotional highs and lows are more evident in teaching, so support of colleagues and family is valuable. You will need some emotional resilience. If you can see some difficult classes as well as ideal classes in your school visit, you're decision should become clearer. I did a cash flow forecast spreadsheet first which indicated 3 years before income fully covered expenditure.The forecast was correct, but I never regretted my decision.