Hi Shelle,
I'm also here from Ireland but on a 489 visa and was initially on a working holiday visa. Being irish, unless our visa is permanent, we are not actually covered by Medicare. Ireland only has a reciprocal health care agreement where you only get emergency a&e cover. That being said, I know some people who only on a WHV have managed to get cover and a Medicare card by applying by post and perhaps not being checked properly. I've managed thus far without cove except for the initial travel insurance. 2 years backpacker worldwide cover which covered me for a GP visit. At least this way you don't have to pay a Medicare levy on your tax as were not eligible for Medicare