I was trying to learn this song and although the verses worked out ok I found the chorus 
the tabs available just didn't sound correct.
After watching various clips of Kate Nash and her band playing live I've come up with 
which I think is more like it.

Chorus
F                                   Am
My finger tips are holding onto the cracks in our foundation,
        G                                       F
and I know that I should let go, but I can't.

Am9                                    G
And every time we fight I know it's not right, every time that you're upset
      F                                      G
and I smile. I know I should forget, but I can't