Main riff:

G |---------------------------------------|
D |---------------------------------------|
A |---------2-2-2-2-2--3-3-3--------------|
E |-3-3-3-----------------------2-2-2-2-2-|

Then (2nd verse on) throw in this every other:

G |---------------------------------------|
D |---------------------------------------|
A |---------2-2-2-2-2--3-3-3-3/5-5/7-7----|
E |-3-3-3---------------------------------|

Very simple and a lovely song - only got the album a few hours ago but it should be right.