If your looking for the easy bass for this song then you want this:
intro
[-----------------------------------------------------]
[---------------------------0--00--2--22--------------]
[-0--0--0--00--0--0--0--00----------------0--0--0--00-]
[-----------------------------------------------------]
play that twice and then play this
[ Tab from: https://www.guitartabs.cc/tabs/p/proclaimers/500_miles_btab.html ]
[----------------------------------------------------]
[---------------------------0--00--2--22-------------]
[-0--0--0--00--0--0--0--00----------------0--0--0--0-]
[----------------------------------------------------]
then play this
[------------------------------------------------]
[---------------------------0--00--0--00--2--22--]
[-0--0--0--00--0--0--0--00-----------------------]
[------------------------------------------------]
and then finaly this
[---------------------------------------------------]
[---------------------------0000--2222--------------]
[-0--0--0--00--0--0--0--00--------------0--0--0--00-]
[---------------------------------------------------]