Fair Call! I am not denying the use of good phraseology and your post prompted me to skim through the AIP to refresh my knowledge. If I am ever not sure what to say (depending on if ATC is waiting for a response or not) I will ask my instructor or make do using as plain and simple English as possible. In either case I will promptly check the by the book way once on the ground.
No matter what though as a student pilot it boggles the mind that people have this slack attitude. When a situation like the above occurs (and so far I have never had the tower come back and say err what?), I feel extremely embarrassed as I judge other pilots by their radio calls and assume you all do the same. How do these pilots live with themselves?