HI Mark
I'm sorry to hear about this.
I don't know what the condition is, though. If you get the bad side effects, would it prevent you from being able to go to work all day every day? If so, would your 457 visa be at risk? What does your Employment Contract say about sick leave/pay and also about holiday leave/pay?
Would the treatment be something you would need for the rest of your life or only temporarily?
Bear in mind that if you get to Oz and find yourself so badly affected by the condition and/or the treatment that you can't work, your 457 visa could well be at risk.
You would get Medicare but if the drugs are expensive then it could cost you an arm & a leg. Please see the links below:
Visitors to Australia - United Kingdom, Sweden, Finland, Norway, the Netherlands, Malta and Italy - Medicare Australia
pbs.gov.au - PBS Portal - Home
If you get a prescription for 2 months supply of Drug A and 2 months of Drug B, then at $31.50 a pop, getting the scrip filled will cost you $63. Prescription charges are twice as high as in the UK and if the drug you need is not on the PBS list, you could find yourself paying around $100 per drug each time.
The standard of healthcare in Oz is miles better than in the UK in my view, but that may not be encouraging if you have to pay a mint for it.
Bear in mind also that you would get
no help whatsoever from the Australian Government by way of Benefits if the side effects are such that you can't work. You would not get the Oz equivalent of Incapacity Benefit or anything.
Whether it might affect a
PR application depends on what it could cost to treat it and whether you would be able to be a fully independent (financially) and tax-paying member of the Australian workforce.
Have you asked your doctor about how incapacitating the side effects might be if you get them?
I would suggest investigating this carefully, my friend.
Best wishes
Gill