Australia is extremely competitive compared to the UK. I think for an international even more difficult, their entry standards are insane. But if that's your dream I'm sure it's possible. For example a 3000 UCAT in the UK is top 7% and competitive for nearly all top universities, while this would only be top 13% in Australia. It seems you need at least a 3100 and closer to 3200 for a chance.
I don't think people typically study internationally without coming from a very wealthy family, but I could be wrong. UK fees for internationals tend to be 3-6x higher than home, quick google of Aus shows home students would pay 8500 while international is 35000 for a science degree.
I'm a physio in the UK. Aus is desperate for health professionals and values UK highly, the equivalency exam isn't that bad. I've had lots of friends move over there. This may be a better route (to study in UK) than studying nursing in Aus, unless you had a scholarship or could afford the fees.
Graduate entry medicine in the UK is 4 years, not 5 or 6.