Another simple but effective Bass Line for "Baby",From UB40s Labour of love 2:

Intro:Play twice(Slide into verse)
G:-------------------------------------|
D:-----55-------------55---------------|
A:---------------------------------5\--|
E:66666--6666633-66666--6666633-(63----|

Verse & Chorus:(Just repeat when & where needed!).
G:------------------------------------|
D:------88-666-555-------88-------88--|
A:-58-6-------------58-6-----58-6-----|
E:6--6-------------6--6-----6--6------|