It's a rainy morning,and only the cat and I are up. I've decided to spend a little time on this melody, but not to learn it and type out every note in my music program.

You can hear more than one version on YouTube. Briege Murphy sings it in Cm, which is the relative minor for the key of Eb, unusually low for a woman, and in my opinion too low even for Briege herself. (She can barely get the first syllable of the song out.)

I'm an alto too, and I can sing a low Eb at home, with nobody else about and being perfectly relaxed. I couldn't hope to sing that low in a concert.

Back to YouTube. Listening to Niamh Parsons, who is also an alto, we move up to Am. I believe it will be easy to work out the chords using Am, G, C, perhaps Em and Dm. I don't think it will happen, but if you get to place where nothing else seems to work, try an E.