Haigh, Saralyn.
Failte romhat ar fhóram!
Although it is not a "beginner" book necessarily, I do recommend An Prionsa Beag, which I have
purchased, and it is a lot of fun to read. In general it follows the
English translation fairly closely, but the Irish idioms are faithfully
executed. You would have to purchase the English version, The Little Prince, separately, but it should still be available.
As to other possibilities, might I recommend that you look around on www.leabhar.com
as they feature a number of books for different levels of Irish
learners. They also include some comic books! One that looks
intriguing is called An Tóraíocht which is a comic-book retelling of Tóraíocht Diarmad agus Grainne.
I have a published version of the story that a friend gave me when I
was in Ireland in the '70s, and it is a challenge to read. The comic
version, based on the panels they show on their website, looks much
simplified as a lot of the actions are visualized so you're mostly
reading just dialog. Anyway, when you go to their Siopa/Shop
link, they break down all their available offerings into categories,
such as Children and Beginners, Teens and Adults, Comics, etc. I
suspect you can probably find something of interest that would be
useful, although I don't know that they have anything with both English and Irish together, if that's of concern to you.
Disclaimer: I am not in any way affiliated with www.leabhar.com or Cló Mhaigh Eo
so I cannot vouch for them, and on the other hand I'm not remunerated
in any way either. It does appear to me to be a good resource for
getting Irish literature in appropriate levels.
Dale D