No matter where you train you can be assured that they have had past students pass through there ranks who are now flying for various airlines, so yes Oats have had a number of guys go to the likes of ryanair and others but the larger majority of newbies getting work are a mixed bunch of other students from all walks of life, NFC in weston for e.g (and no I am not assosiated with them) have had a lot of guys go into ryanair and cityjet over the last number of years so dont get hung up on it, just do what suits you and your pocket.
Pan aviation are'nt to bad and you should'nt have any reservations about applying to an airline with either the IAA or the CAA license. There may be just a small paper work issue in relation to it but if the company wants you they are not going to turn you down due to your JAA country of license issue.