Write the blessing in my tablet's drawing app using the / slash 'nib'. I wrote it in green and completely forgot about using uncial lettering. This is hand lettered. Upload to an online image editor and convert to black and white. Find another online image editor that converts photos to coloring pages. Usually that conversion does not work well on my images but in this case I wanted the lettering to lose the insides. That worked well.
The lettering took up so much space that there is no real place for decoration. But you have a lot of letters to color! I hope this can print out nicely as a gif file. I will later put it in pdf form. And, here it is, a pdf on my Etsy - Irish Blessing coloring page pdf a $1.50 download.