Agree with cactus and others who have pointed out that the OP's financial argument does not stack up. Short-term thinking.
If you're a primary teacher, after a gap of, say, five years, it could well be hard to find another job, especially given that you will be more expensive than NQTs, more people become teachers in a recession etc. You may find it particularly hard to find a part-time role.
Unless you decide to and manage to return to teaching, you will need to get a different job (probably for much less money, at least initially), retrain (which costs money), make money here and there from tutoring, small business etc, or rely on your DH's income long-term (which is risky in many, many ways). And you will have had a big break in pension contributions. And (if you go to a job other than teaching) you may have to work the holidays, whereas if teaching you could have the holidays and associated reduced childcare costs.
I am in a similar situation (though not a teacher) and would love to stay at home for several years, but would never, eve quit work - especially good-quality, reasonably well-paid, part-time work - because it is too damn risky for me and the whole family.