Glacier, Welcome with open arms!!! Always great to have new folks here!!!
:D ^_^ B)
With no time limit your adventures could be endless!!! You just need to work a bit to subsidize your travel costs after the 4000E is gone.
Have you considered this Australia to say Turkey ( I know there is alot of Australian History there) Making your way north through the former eastern bloc countries, Bulgaria, Romania,Hungary, Slovakia,Poland into the Czech Republic Those countries will be your most affordable I would have to say, then you could start making your way west through the mosre expencive countries, Austria, Switzerland,Italy, southern France you should get some $$$ relief in Spain and Portugal, heading north again through western France into Paris, here you could continue north into Germany, Netherlands and Belgium, or cross over into the UK...by the time you get to to UK you will be running short on money for sure, find some work for a while, Labor work, bar tender, waiter, what ever, get your wallet fat again and see England, Wales, Scotland, Northern Ireland and Ireland. You could end you adventure there
Keep on going...book a flight out of Dublin or London for New York, Boston, Montreal, or Toronto and trek across North America. Start in NYC take a train to Montreal, bus it to Toronto ( YEHA!), Bus it to Detroit Michigan USA, shoot across the border states which are a bit more interesting than the Canadian Praries When you get to Montana head north into Calgary Alberta Canada, hitch hike through the Canadian Rockies in to Britsh Columbia enjoy a much hospitality in Vancouver, make your south back into the US through Seattle all the way down into California and fly home to OZ from there.
Now the North American part is just an added bonus if you have the time and money to do it, but the rest could be a guide line for you to base your trip on, basically what I think will be the cheapest to the most xpencive.
Hope that helps even a little. You should be able to find most of the imfo you require for yout trip here, just browse alot and check in for new and updated information!!!