okay i've seen videos of sam playing it in C with a capo on the fifth fret, but this 
is what i've worked out with my guitar teacher and it sounds quite the same and 100% 
i think. so you can play it either way.
that's the version capo-less people.

The song starts like that:

e I---0h1----------------|I
B I--------1------1------|I
G I-----------2----------|I
D I----------------------|I
A I----------------------|I
E I----------------------|I

and goes on with:

Verse:
I   F   I   F   I   F   I   F   I
I   Am  I   Am  I  Am   I   Am  I
I Bb#11 I Bb#11 I   F   I   F   I
I   C   I   C   I   C   I   C   I


Refrain:
I  Bb   I   Bb   I   F  I   F   I
I  Bb   I   Bb   I   C  I   C   I
I  Bb   I   Bb   I   F  I   F   I
I  Bb   I   Bb   I   C  I   C   I


F should be played as ( X X 3 2 1 1 )
While Bb#11 is ( X 1 3 3 3 0) i know it sounds dangerous, but it isn't at all. You 
here the high e string

I recommend to play the chords in the verse like this (it's not completely what is 
in the song, but it sounds more expressive to me if you don't have any rhythm section):

   F

e        I-----1-----------1---I         I-----1----------------|I
B        I-----1---------1-----I         I-----1----------------|I
G   3x   I-----2---0h2---------I  then   I-----2---0h2----0-----|I
D        I--3------3-----------I         I--3------3------------|I
A        I---------------------I         I----------------------|I
E        I---------------------I         I----------------------|I


  Am

e        I---------------------I          I---------------------|I
B        I--------1------------I          I--------1------------|I
G   3x   I--------2-------0h2--I   then   I--------2-------0----|I
D        I--------2---0h2------I          I--------2--0h2-------|I
A        I---0-----------------I          I-----0---------------|I
E        I---------------------I          I---------------------|I

  Bb#11


e        I------------0---------------|I
B        I-------3-----3----3---------|I
G   2x   I-------3----------3--I------|     then 2x F (like above)
D        I-------3----------3---------|I
A        I---1------1----1------------|I
E        I----------------------------|I

  C

e        I---------------------I         I---------------------|I
B        I-------1----------1--I         I---------------------|I
G   3x   I-------0--------0----I  then   I---------------0-----|I
D        I-------2---0h2-------I         I-------0---2---------|I
A        I---3-------3---------I         I---3-----------------|I
E        I---------------------I         I---------------------|I

In the Chorus the strum patterns are quite the same.

----------------

with a capo on the fifth fret the chords are
F     =   C
Am    =   Em
Bb#11 =   F#11
C     =   G

the #11 problem is much easier:
by playing the Bb as an F (X X 3 2 1 1)
the F#11 is played as (X X 3 2 0 1)


byebye