This is only part of the song, but I haven't seen any bass tabs for Ambling Alp 
anywhere so I figure this is better than nothing.

G|-12-12-12----------12-12-12----------|
D|----------14-14-14----------14-14-14-|
A|-------------------------------------|
E|-------------------------------------|

G|-12-12-12----------14-14-14----------|
D|----------14-14-14----------14-14-14-|
A|-------------------------------------|
E|-------------------------------------|

G|-12-12-12----------------------------|
D|----------14-14-14-12-12-12----------|
A|----------------------------15-15-15-|
E|-------------------------------------|

G|-12-12-12----------------------------|
D|----------14-14-14-12-12-12----------|
A|----------------------------15-15-15-|
E|-------------------------------------|