I've just seen Series 1 for sale in Australia through the ABC Shop:
Green Wing - Series 1, 3 DVD Set, $39.95
Rated: MA
Duration: 468 mins.
Released: 2008
PAL Format - Region 4 DVD
ISBN / Catalogue Number: R-107737-9
Does anyone know when/if they're planning to release a Region 4 version of the 8 DVD Collector's Box Set?