The UK, and the NHS do not care about the requirements needed to keep your Aussie visa current. They are only concerned with where you live, where you are a resident. Many people in Aus could claim they are emtitled to use the HSby your reckoning but it just doesn't work that way.
If you want repatriation to the UK you will need a UK based insurance policy, or the insurance policy included with your credit card. If you are a UK resident that should be easy enough to organise. However if you need to claim the insuance company may start to query where you are actually resident. Possession of a visa will not come into it, its a case of "where is the centre of your life".
If however you prefer to view yourself as an Aussie resident then you would be repatriated to Aus. Its just as simple as this -repatriation means that you are returned to the place in which you currently live. although some of us wish it were different, we can only live in one place at a time.

I only have UK credit cards. I use a debit card in Australia. I cannot get an Australian credit card as I am retired with no Australian income.
Checking various UK credit cards it seems that their travel insurance offers are up-to the age of 70. I am 73

It does not seem that a credit card will provide the insurance cover that I would like at a reasonable cost.[/QUOTE]

How long have you lived in Australia? We have lived here since 2003 on a long term temporary self funded retirement visa, don’t have PR, all our income is from UK, and we had no problem getting Australian credit cards. Have the rules changed?We are over 70 and use the cards travel insurance when we go back to UK every year, but only go for 3 months.
We definitely don’t qualify for free NHS, even though we still have property there, pay tax there, as our main residence where we spend most of the year is in Australia. Do you have to spend a certain length of time in UK every year to qualify?

I did once when living as an expat have a letter from the NHS questioning my status, so they do check up, and was specifically asked if I was absent for over 3 monthsI as if over 3 months you were then supposed to reapply on your return.That’s how it used to be, has that changed?

Its not down to spending a certain amount of the year there. One is entitled to NHS care once one moves back there, at once, but when visiting, nope.
Its down to where the centre of life is. If one maintains a home, banks there, pays utility bills, fills in the UK address on forms when asked where you live, is on the electoral role, calls the UK home, etc etc then thats considered as living there. The NHS may ask for utility bills, GP registration, bank statements etcas proof of residence.

From what the OP has written she is not resident. Therefore she can't get travel insurance as a resident. She'll need to get the insurance as an Aussie resident a d if she needs repatriation then (unfortunately) she will end up in Aus. OP, I do feel for you as I would love to find a policy that says simply "if she dies en route, take her to the UK" but its not going to happen.
There may be some companies that do one way insurance, aimed at migrants, I think Gowalkabout was one for people moving south, but I don't know of any going the other way. And you ned to think about this differently, you are not just asking for insurance for the 3hours in transit, you need it for the whole flight. Thats 24-36hours, If you are taken ill on biard a flight and they have to divert you are going to need insurance to cover the care and the repatriation from wherever you may be.

Our credit cards are Commonwealth bank, do you have a permanent address in OZ? Although having said that, our UK accounts have our OZ address and we have their credit cards, so don’t know if Australian banks are the same.
I know as far as you are concerned you qualify for NHS, but I Seriously think if you are ever questioned by a follow up tel call as I was you might find you aren’t. Even though you maintain a property etc in UK if you are Regularly out of UK for 6 months, so away for over 3 months, I am fairly sure you are supposed to tell your surgery, if you haven’t then I suppose no one has chased it up. Not idea why I was checked, but in my case I was ok as never away for 3 months as our children were in school in UK.

I'm fairly sure that if you are on a CPV you should be filling in an Aus tax return, declaring your UK income, and thus not being taxed in the UK, due to the dual tax agreement. Thats certainly the case with most CPV holders.
Technically you should not be registered with a UK GP if you are an Aus resident. However as you seem to be treating the CPV like a tourist visa, and claim to be a UK resident, then you should be looking at UK based insurance and (possibly) credit cards.
I'm afraid that having handed over a small fortune to get the visa counts for nothing. most of us have done that one way or another.

The other thing that occurs to me is -how long have you held a PR visa? Are you sure you will qualify for a RRV when the time comes?

I'm assuming that the OP calmly makes use of Medicare whilst in Aus, then the NHS whilst in the UK. Good trick if you can get away with it, nicely funded by the rest of us......

Interesting situation on tax. At the moment as temporary residents in Australia, with no income here, we are fully taxed in UK. However if or when our CPV ever comes through, this will change and as far as I know we will become Australian tax payers, in Oz with the double tax agreement. I might have the terminology wrong as no expert at all, but we definitely become Australian tax payers when we get our PR.

Even though the OP has never made any claim on Medicare so far, once you are in your 70’s more health problems rear their ugly head. 2 years ago I had almost no health problems, can’t say the same for the last 2 years.

Interesting situation on tax. At the moment as temporary residents in Australia, with no income here, we are fully taxed in UK. However if or when our CPV ever comes through, this will change and as far as I know we will become Australian tax payers, in Oz with the double tax agreement. I might have the terminology wrong as no expert at all, but we definitely become Australian tax payers when we get our PR.

Even though the OP has never made any claim on Medicare so far, once you are in your 70’s more health problems rear their ugly head. 2 years ago I had almost no health problems, can’t say the same for the last 2 years.

sorry double post

Certainly an interesting one with the tax situation. He would need to be tax resident in one country and declare the income from the other. Presumably he is in receipt of a UK state pension. OP, I am not expecting you to answer any of this as it is my musings on the situation, but someone in Aus claiming a U K pension as an expat doesn't get the annual increase. If you are a UK resident you would. You would however benefit from Aus discounts for seniors, and some centrelink benefits. Then by claiming you are also a UK resident you get all the UK benefits and allowances, reduced council tax on your property etc.
Its questions like that which mean you must have a home country, you cannot be resident in both, and in one your status must be thar of a visitor.
And in turn questions like that lead to the issue of insurance. It should be done from your home country, and repatriation would be to that place.

Not sure if it helps the OP but my Aussie Amex card provides one way insurance to the UK if I book the flight with them, covering the flight amd the transit. ( I know the OP seems to think they only need transit but you do need the flight as well) . They say for anything out of the ordinary to contact them -maybe worth a go Maybe the OP has a UK Amex card? If so might be able to work something out between them.
Or contact whoever insured the last flight from the UK to aus?