Yes you definitely can, but the cost is outrageous, £7 or so for 30p worth of plastic, if your hotel doesn't have adapted plugs in it - any the international chain hotels certainly have them - then you best get then in Woolworth in Australia. In addition to WH Smith and Dixons, they are also on sale in the main Duty Free shops and Boots. The latter may well be a bit cheaper than the other locations.