You’re looking to blame someone for the situation you’re in, You’re not wrong to feel cheated for the life you wanted, but you and your husband are stronger together.
At the moment, you can’t see any light at the end of the tunnel, so that’s why you’re searching for something to make you happy.
Unfortunately, as PP have mentioned, your child could be in a special school and you could have your ideal job working in a different school, but you’re still likely to get those calls to pick up a poorly child, or medical appointments, or one of their schools are closed/inset day etc. Your husband will still expect you to be the default parent.
If you can, get a carers’ assessment done by social services. That will identify where you need support (LA may say they don’t have money) but it’s a starting point.
Eventually, you could get direct payments that could enable you to employ a personal assistant for your child, giving you time to do something for yourself.
Find out about local volunteer positions. I used to be a Face to Face volunteer befriender. My hours fitted around my child’s school and people understood when the sessions had to be cancelled at short notice. It also gave me a reference for when I got my school job. Anything like that on your CV makes you stand out.
Consider looking at an Open University degree. You can do that fully in your own time, at home, at your own timescale. You won’t start paying back funding for your tuition until you have a job paying over £28,000.
I know from experience how awfully challenging your life is, but if you can change the focus it may help.
I wish you luck.