At present they are not available. The original idea once upon a time was once the question bank reached a certain number of questions (10,000?) it was to be released publically like the way the FAA does things.
The best way to test yourself and really see how bad the JAA questions are is to either use the school you are studying at's feedback or bristol.
Oh an example of a bad JAA question while I'm on the subject: What is oil/fuel heat exchanger for in a jet engine?
a) to cool the oil
b) to heat the fuel
c) something else
d) another option
Jamo