They can never be happy for me?

I think that as you proceed through your course, you'll realise that you perhaps chose this exact route because subconsciously you wanted to pin down exactly why these people are so lame, psychologically.

And you won't be able to go back from that realisation, and education, power and knowledge.. Your life will improve vastly as a result of your newfound intolerance of their small minded negativity. And on some level they know this, hence why they try to cut you down to size.

No one gets to clip your wings, unless you allow it by holding your wings out to them to be clipped. Fly away. Save yourself.

Go for it OP. We mostly regret what we didn't do, the chances we didn't take, the opportunities we didn't follow up. I did my degree aged 40 and enjoyed a 22 year long fulfilling career from it.
Just like in your case, my own mother wasn't exactly encouraging either but I didnt let that stop me or take away from my enjoyment of the university experience. Well done you and good luck. 💐

What are the wider ways they have put you down in the past?

My immediate hunch was embarrassment rather than jealousy - they know they don’t have the energy or focus to do anything for themselves so they respond with negativity to anyone taking a positive step forward for themselves.

What do/did they do for work? Do they consider you to be “up yourself” because you put effort into your work and wider life? (in my wider family this is shorthand for anyone who got a degree, basically)

They sound like the types who don’t like people “getting above their station”. You just need to ignore and soar - let the haters hate. You’ll be doing something you want to do with your life and they can just pickle themselves in their negativity.