I am so boiling mad on your behalf, I might burst into flames.
But first, bloody well done to you for retraining and getting work in programming!
As he has proven, no, you can't look after a three year old and work at the same time (and I certainly couldn't programme in those conditions). His argument about being interrupted at work is insane. The interruptions at my work are people who will ask if I'm available and will go away and come back later if I'm busy - unlike a toddler. But don't get sucked in to trying to argue with him.
He knows he's being unreasonable. He KNOWS. He's just trying to manipulate and pressure you into giving up work.
I agree with everyone saying your top priority is to find some childcare for the holidays, possibly a bit of extra childcare for term-time. Do not give up work, do not become entirely financially dependent on someone with that attitude.
Also, it's not him giving up 30 pounds an hour for you to earn 8 pounds an hour. It's him giving you some time to earn some money, NI contributions, pension contributions, self-worth, confidence, future greater earning potential, future promotions, being a strong role model for your son ... I could go on.
For the last couple of years, my DH has been retraining and I now far outearn what he does but, do you know what? Together we have made plans and changed hours, timing, switched leave etc. to make it work for him, because I'm happy he's doing something he enjoys and we're a team, and we are planning for me to do the same once he's a established in his field!