Having seen many of the cadets from previous years it is fair to say the vast majority are Irish, and a trickle from the UK. There is however no official evidence that preference is given to Irish nationals. I wouldn't like to be seen discouraging anyone from attending, however if you're coming half way across the continent, missing work etc and paying a fortune in the meantime I would certainly be giving it some hard thought.
If you think it is for you, then I would seriously focus on trying to convince the AL team that you are not just using them as a means of learning to fly and then running off once the bond is over. I've said this before, they are more likely to go for an Irish person imho simply because they will more than likely stay and pay back their dues to the company !