I was (am) in the same situation as the OP, he was a carpenter when I met him and I was in my last year at university.
I didn't give a second thought whether we were culturally matched, but I was more cultured, travelled and educated than him.
BUT, only because he hadn't had the opportunity to go to university and take a different path in life, his parents didn't push him like mine did (I put myself through uni by the way) and he didn't know what t he wanted from life let alone how to make it happen.
He is very intelligent adn since we have been together he has moved up in his profession and is now a site manager doing a degree course to take him even further.
He says he wants to progress partly because I give him nudges and tell him he can be whatever he wnts to be, but also when the dc's came along it fired his need to provide and earn enough money to buy a house, cars and all the other stuff that come with it.
I am now a SAHM (wasting my hard earned education and culture ).
I sometimes use words that he doesn't know but not because I'm more intelligent than he is , but because I'm such a book worm I come across these words. I just tell him what it means!
But I don't know everything because I've been to uni, there are lots and lots of things that I don't know that he will have to explain to me.
I don't think you're a snob and you're right to give these issues some thought, but most of them needn't be a problem unless you make it into a problem.
Forget about his manners, find other people to share your interests.
But I would be a bit cautious if you're not allowed to assert yourself, what makes him upset? Is it because he feels threatened by you?