It's sensible to have a back up plan for ANY job you do. I've recently just created my 5 year plan - and I want to be out after that point. It's not that I don't love my job, I do, but I want to do other things and create a job / business which is much more sustainable and not solely dependent on my health, age or ability (this is my fear, that I get I'll and can't work - what then?!)
I've always wanted to do photography. I've just signed up to a beginner course to learn, which then gives me one opportunity in time to become a professional photographer. I could even specialise in boudoir / glamour shoots due to my experience and knowledge in this industry.
But for something solid, I want to get into property.
It's a huge leap to jump from working to studying. Infact, going back to education after any break is terrifying and a HUGE learning curve. I went to uni for my degree at 22, after 5 years of leaving school, and that was very difficult in the first year to adapt to an academic environment again. I like other's suggestions of the Open University to begin with. It will allow you to dip your toe in and plan it around other committments you currently have.
I'm not sure which country you are in, but in Scotland, every person gets an Independent Learning A(count?!) which gives them a grant of £300 or so to use for an educational purpose.
I really wish you a lot of love and support through this time. Please feel free to message me if you want to chat further xx