As an addendum to my initial post, I was of course refering to the National Archives in the UK, however you will be able to obtain his service record from the Australian National Archives, you can do this on-line & can either have it mailed in hard copy form or alternately you can view on line after the clearence of the record which ususally takes about 1 month after ordering.
Here is a link:
RecordSearch - National Archives of Australia
Regards
simon