I found that the cold in Melbourne was only a problem when the overnight temp drops to below 10 deg. Thank goodness for winter doonas.
During the day I would wear a suit and on the very cold days wrap a scarf round. Other than that I found the sun warms you up when outside (Hot Cold we used to call it).
I've been back in UK now for 10 months, and can't acclimatize at all. The temperatures seem to stay in the colder than I would like range and can't get used to it at all.