Firstly , Australia forces it's citizens to do a 2 year resident before being able to go overseas ,so that's why you see many going back for their "2 year jail term"
You also lose your rent assistance allowance etc if overseas
But...unlike the UK the Australian system is Means tested so you aren't eligible for old age pension (67) if you have more that I think 200k,? in your bank account,so no use retiring at 67 with retirement savings you won't get the pension
,better to retire at 62 and SPEND it all before 67 if you want the pension !!!