Can I come back?

This is a weird query. I'm an Aussie citizen but have lived and worked in the UK now for 30+ years. I've applied for a short-term job in Australia (1 year initially, maybe a bit longer) so my wife and I can look around at leisure before I take state pension in the UK. I have two possible problems:

1. My wife has rheumatoid arthritis and is on serious medication. She'll probably try to arrange a bulk pickup of medications before coming out and then come back a couple of times during the year and do the same again before coming back out. We're hoping the GPs here will sign her off for doing that. Question is, are there any problems we could face if she needs any emergency care while we're in Aus?

2. I've just (today) found that I may have a circulation problem and am due to have some blood tests and an ultrasound scan. I've not got dates for those but am hoping they can be done before I leave in about 3 weeks. Doc says they'll likely come back clean since there's only one indicator but what would be my situation in Aus if I need treatment for whatever is found? And should I drop the idea of coming back for that long and just stay in the UK? (I'd have to tell the company I'm hiring into that I'm backing out of the job but I'm sure they'd rather know now than just before I'm due to leave here.)