Cheap camping down under
A mate recently told me he'd bought a second hand camper trailer for five thousand dollars (about 3 Grand in Pounds), able to be towed by a common ol' garden variety Holden which you can pick up for a couple of thousand dollars (about a grand in Pounds). The camper trailer had inner spring mattresses and a pull out kitchen drawer.
At the end of the trip, if coming over for a few months exploring what this BIG country's got to offer in way of beaches, hot pools, tropical islands, coral reefs, high waterfalls, rainforest and so on, then you just sell it on at the end of your trip for around what you paid for it, if undamaged. Easy.
http://www.cavaliercampertrailers.com.au/kitchens.shtml
There are half a dozen camper trailer manufacturers across Australia, and each has its own unique little features, but basically are much the same in price.
Look for a good one about 5 or 8 years old which someone doesn't use anymore.