Sorry, Magpie. I didn't read your posting carefully :-(. You know about the McQuaid book. The chord chart in the site I mentioned will give you the same problem, I think. Unfortunately a friend has my copy of the book, so I can't make any comments; but for the chord chart at the web site, the first chord shown under any letter is the "open" chord for that note and should probably be learned first and used when that chord is called for. Also, do read the "theory" because a lot of the chord progressions we are used to with blues and popular music are not applicable to Celtic music.
Some of the other sites that the one I mention is linked to might give you more info.
There is a video lesson put out by Homespun tapes (http://www.homespuntapes.com/) called "Celtic Instrumentals for Fingerstyle Guitar" by Al Petteway which is devoted to playing in DADGAD tuning. I haven't seen it, so I don't know how good it is; but the description sounds good.