There was a whole Australian album that "Hedgehog Pie" made in the past - it was abit tonge-in-the-cheek, but had a great number called "Christmas in Australia" which would be suitable for this time of year. All I can remember is the chorus:

Christmas in Australia is Christmas in paradise,
Christmas in Australia is (boom, boom) bloody nice.
Bruce is cuddling Sheila and Sheila's cuddling Bruce,
And if you haven't got a Christmas suntan,
You're a pom and no bloody use !

Vectis has already mentioned Martin's songs and two of my favourites from his repertoire are GENTLE ANNIE and SAILOR HOME FROM THE SEA (lyrics by the late Dorothy Hewett).

Barry Humphries (Dame Edna), under his Barry McKenzie guise, wrote some wonderful "Ocker" ozzie songs such as "Chunder in the old Pacific Sea" and one about an ozzie who's feeling pissed off in London, with the wonderful words:

So I told him straight - I'm Ozzie mate,
And I'm bent on getting plastered.
Coz the beer's all crook, and the girls all look,
Like you, you pommie bastard.