Make them a CD or send them the songs that you've rehearsed.
Something tells me that you play while they sing. While that works for a lot of people, it doesn't work for everyone. If I'm right, they need you to feed them the words and such (a daunting task, I know).
How inconsistent is 'inconsistent'? Meaning, on average, how many folks do you have on Sundays? If it's the same ones, you may want to cut bait on the rest.
As for songs, 'Lord, You are good' is quite easy.
'I give myself away' is also easy.
'Bless the Lord with me' is easy.
'Holy are You, Lord' (Joe Pace)
That's all I can think of off the top.