Of course it is for someone of your age!

I had a successful career before I had my children but didn't want to return. I volunteered in school while my children were young, found I enjoyed it so did the training. I was then offered a job in the school and the rest, so they say, is history. I was just a little older than you at the time. I'm sure many secondary schools would love to have someone with your experience.
My aunt is 85 and still goes into school to hear children read on a regular basis.
Good luck