Ok, so how would the College know that you had parental responsibility? As you say, you haven't seen him for years so what is to say that he hasn't disowned you in this time and wants nothing to do with you?
In any case, once he reaches 18 the College won't tell you anything at all. For under 18's we will send letters to the students with copies to the parent (or named contact) - once the student reaches 18 then the parent gets nothing unless the student chooses to give it to them.
You obviously don't even know which (or even if!!) College he is going to. How are you planning to get this info?