Hi Nicola..
As I understand you have plenty of time getting it all organized and to gain as much as info as you can. Get your motorbike licence in OZ as soon as possible, it will do in Europe (obtain an international licence when you leave, which is just a fancy translation really). Get some experience on the bike, Melbourne and surroundings has it all, busy city traffic and great backroads!
Roads in Europe are generally fair to good, you´ll quickly get used to driving on the right side (faster than you think). There might be some local differences in driving styles but again with your "Melbourne" background it shouldn´t pose any problems. Compared to Australia, Europe is quite compact and with an average of 250 k´s per day you can cover a lot of Europe and see lots of different things. Petrol will take a bite out of your budget, it is expensive in most European countries so bring some light campinggear so you can safe some money while (wild)camping. And maybe a little stove to cook a simple meal (noodels etc.) You must be able to do it at 60 euros a day (average). I would recommend a (Japanese)bike which is sold in most of European countries, nothing too fancy, go for reliability!
If it is a common bike there will be plenty of servicepoint/spare parts available. For you as an (Irish) Aussie, Britain is the best starting point , get your bike there if you can and sort out all your paperwork there.
Plenty of channel crossings to mainland Europe available, it pays to shop for deals! Most of it common sense really and there are always great tips on this site to get you sorted. Issues like wild-camping or the worries of travelling solo as a female, doing small repairs yourself etc..its all here!
I am happy to give you more info on Europe, I (born in Geelong) live and work with my Dutch wife and children in Amsterdam and done several trips around Europe...

Go for it!
Robert