I think you just need to be interested and engaged - and you are, judging by the question you asked in your OP.
My father didn't go to university but was one of the best educated and interested/interesting men I ever met. I have met people with advanced degrees who have no curiosity and no conversation.
I would say the following:
Have an interested, engaged, curious loving home where their friends are welcome, their thoughts are listened to, they are part of the conversation, they are valued. This is the single best thing you can do for your child. It is harder if you have to work shifts/second job etc but it is essentially free.
Join a library. If possible have books in the home. When your child expresses interest in something, get a book out of the library on it.
Find out the cheap/free times at local museums and go there.
Ditto, find any free camps/mentoring etc that is there and get it - I have a friend who does this for her kids and they have really done amazingly - neither parent went to uni
Read a book together as a family - at the beginning maybe read aloud, and then have everyone read the same book over the summer for example.
Google and come up with interesting questions to ask at the dinner table and ask them. Make dinner a time for talking.
Be interested and engaged in their school if possible.