I’ve been thinking quite a bit of these things recently, having got caught up in the background-scenes of a fic of my own (unlikely to be finished, but still), and to me it makes sense that each grade would receive education on a kind of general need to know level, according to the tasks that persons of their class are expected to perform in the Federation society. Assuming that the Alpha grades don’t get to do all the more complex jobs (which seems unlikely), that means that at least the Beta grades would have the chance of a higher (if likely censored) education. In Avon’s case specifically, I suspect that his scientific curiosity in combination with his hacker skills probably could have given him an extensive "education" as well, quite regardless of whether he was meant to have it or not.

Actually, it is on record that Blake is an Alpha grade – or at least that Vila believes that he is:

(From Shadow)

CALLY: Blake has led a sheltered life!?
VILA: Look, he was an Alpha grade on Earth. A highly privileged group, the Alphas. Wouldn't last five minutes among the Delta service grades where I grew up.

...But I agree with you that he would really fit the part, regardless – certainly much more than Avon does.