I too have the "Teach yourself Irish" but was not real pleased with the layout of the book but still plugged on through it. I also found CD's in Irish at:
http://www.pimsleurdirect.com/collections/pimsleur-irish
These are real good but lack any books which is the only downside. I converted the CD's in my PC to mp3 files and put them in my mp3 player and now I have them with me whenever I take a walk or go on a long drive. I am one of those learners who does better by "hearing" and find this way a quiker way to retain the Irish words and phrases.
Slán,
Doug