In my experience, if you can't sing on key, pitch correction will make it much worse - not better. Pitch correction is for someone who does sing bascially on key, but wants it to be perfect.
However, if you choose for each song the scale that you'll be singing in - ie you knock out 5 of the 12 notes in an octave - you may have more success.
The principle is that pitch correction corrects you to the closest note. If you are closer to the wrong note than the right one (it happens even for people who think they CAN sing on key), it will pitch correct you the wrong one.
Chony