Marie i've been adjudicating scor competitions in Ulster and Connaught for about 12 years now. the advice i would give you is to go for something traditional - stay well clear of the likes of "Grace" or "A song for Ireland or anything too commercial. Even though we're not allowed to judge on the choice of song we have to judge how you interpret it and its very difficult to bring anything new to this type of song. A simple song sung well is a lot better than a difficult song that you can't do justice to. And don't forget the performance has to last less than 6 minutes. 1 of my students won the all ireland Scor sinsear with the "the flower of Finae" another got to the all-ireland with "the green linnet".

hope this helps!