Half moon - IREX isn't too bad if - like any exam - you know your stuff.
The big thing I would imagine for you would be working out what is different to what's at home.
For example, a sector entry is a sector entry anywhere in the world but the Aus Alternate requirements are different to those anywhere else I know of - expecially the application of buffer periods. OZ is also the only place in the world I know of where a METAR/TTF is valid for three hours.
Try and find the differences and make sure you know where to find them. For the exam you don't have to know them - only where to find them!!
Would also recommend the Chris Henry book if it's still out there for IREX. Excellent sample exams with good practical basis.