Soodlum's 100 Irish Ballads, volumes 1 & 2, and 100 Great Scottish Songs, but you may want to adapt the chord changes a bit. Ken Perlman's Traditional Dance Tunes for Acoustic Guitar (Mel Bay), the Celtic Harp, Pocket Tin Whistle Tutor, Fiddler's Fake Book...There's a DADGAD book that's pretty good...

Make these songs your own by not accepting printed arrangements as gospel, but as a starting point.

Peace, and good luck, Mooh.