This is better than some of the tabs I've seen for the song, but I suggest using the following chords: Main progression: C2 Em7(just drop to B on A string, keeping rest of C2 chord intact) Am7.
The C2 and Em7 substitute for the C and G/B wherever they are shown.
When singing 'Alleluia' four times, play: C2 Em7 Am7 Fmaj7 D Al le lu ia Al le lu ia Al le lu ia Al le lu ia