The chorus chords are: G / Am / C / Em

Far as I can tell, the only chords in the song are G / Am / C / Em

It starts on Em, strum along until you change to G (listen to the recording to get it 
it's on the '...four walls' line. The sequence of chords for the verses go:

Em / G / Em / Am

then

C / G / C / Em

then off to the chorus so it goes... (lyrics waaaaay off!)

G                  Am
a beep beep beep
C                     Em
it's a home for me
G                      Am
scream scream scream
C                                    Em
oh the happiest place to be.

Sorry there's no real detail but it's such an easy song (although a great one), if you 
play open chords and know the recorded version (on the bside of 'Well, love does furnish 
life') then you're laughing. Enjoy.