What is the difference between propositions and judgments?
First, you should know that, in general, there is not consensus about these terms and their definitions depend on the system in which one is working.Since you asked about intuitionist type theory, I'll quote Pfenning:


  A judgment is something we may know, that is, an object of knowledge. A judgment is evident if we in fact know it.


Propositions on the other hand, according to Martin-Löf are sets of proofs. In this interpretation, if the set of proofs for a proposition is empty then it is false and otherwise true.


  A proposition is interpreted as a set whose elements represent the proofs of the proposition


says Nordström et al.  On the other hand, in classical logic and in general, propositions are objects expressed in a language which can be either "true" or "false".

To give you some extra intuition; from my point of view, judgments are metalogical and propositions logical.

I suggest "Constructive Logic" by Frank Pfenning, "Proofs and Types" by Jean-Yves Girard and "Programming in Martin-Löf's Type Theory" by Bengt Nordström et al. All three are freely available on the Internet. The last one is probably the closest to what you want as it is oriented to programming and goes into great detail, at length, about the meanings of these terms and many more.