So as i'm trying to book my flights out of OZ i'm finding that most travel centers do not allow you to book flights 18 months in advance. Anyone with experience have any advice on how to secure a flight (And price) out of Australia so far in advance?

The plan is to fly into Australia August 12, 2011 and return as my working holiday visa expires in August 2012.

I don't think it's possible.

Airlines typcially release the inventory somewhere betweem 330 - 355 days in advance.

I wasn't aware you needed to show proof of return flight with a WHV Too many variables to make it viable.

The only way around this is "around the world fare " with a twelve month life,
a bit more expensive but you can travel at any time and know their is no more to pay.

Any 'regular' (i.e. non-special discount) fare shoudl allow you to reschedule your return date.

So book it For August out - llate August return and then reschedule the return nearer the time.... too easy...

You'd have to continually reschedule it month after month though if you booked late August return??

Better to buy an open dated return where no return date is specified at the time of booking - if possible.

If not you have to make sure you buy an airfare which has 12 months validity, some are only 3 months, typcially cheaper.