Do British travellers to Australia have to pay for healthcare?

Please could somebody let me know what the arrangements are if you are travelling to Australia on holiday as a British citizen and you need to go to the doctor? Do you have to pay or is it free? If you have to pay, can you claim it back? Presumably hospital treatment isn't covered (except emergencies perhaps?). And what about prescription/drugs charges if you're prescribed anti-biotics or something? I'm interested to know - and obviously I know that your travel insurance will cover most things but I want to know about the arrangements between Australia and the UK aside from any insurance a traveller might have.