Hi Chris
If you could afford to commit the money (lots) for 4 years and would ahve enough money left over to pay for the CP visa on top once it comes through, then a subclass 405 Investor Retirement visa would enable you to "live" in Australia whilst your CP 143 visa is processed.
Details of the Investor Retirement visa are here:
Investor Retirement (Subclass 405)
http://www.immi.gov.au/allforms/pdf/1248i.pdf
I'd have thought that the Investor Retirement route is overkill, though, once a CP application has been lodged.
If you are content just to "visit" Australia, as opposed to trying to move there to "live" there, I'd have said that a better option would be a subclass 676 long-stay tourist visa instead.
Please see here:
Tourist Visa (Subclass 676)
DIAC in London are usually pretty good about allowing British Parents to stay in Oz for 12 months, particularly if the Parents have applied for a CPV.
If you want 12 months, then your best bet is to make a paper application using Form 48. This will ensure that the tourist visa application is handled by a human in London. Send a copy of the acknowledgement letter for your CP application, plus a covering letter explaining that with the current delays in CP processing, by spending time in Australia you can at least tour suburbs etc and get an idea of where you would like to settle etc.
Please see here:
Tourist Visa (Subclass 676)
If either of you are 70 or over then your own GP must complete a simple form of Medical Certificate, which should be submitted with Form 48. Please see here:
Visas and migration - Australian High Commission
Click on the Health link. I have given you a wider link than you need because the AHC website contains lots of other useful info besides.
If oe of you is 70 or over, you do NOT need provate medical insurance, regardless of what it says on the main DIAC website. That is aimed at people from all over the world and few countries have Reciprocal Health Care Agreements with Australia. However, the UK does, and it counts as medical insurace for the purpose of a subclass 676 tourist visa.
Be aware that a 12 month stay on a subclass 676 tourist visa will inevitably attract Condition 8503 - no further stay. The effect of this is that you will have to leave Australia when it expires. Depending on what happens with processing times for CP visas, DIAC might be happy for you just to nip to Auckland, Bali, Singapore or similar for a week so that they can give you a new subclass 676 visa permitting another 12 months in Oz.
However my strong advice is do not sell up in the UK. Let your house in the UK to tenants instead, but hang on to it for now, I strongly suggest.
My reason for saying this is that if the Minister declines to increase the quota of CP visas, then the processing times for them are likely to stretch to 2-3 years. Tht is too long for comfoirt, in case oe of you develops a major health problem before DIAC is able to grant your CP visa. I would keep your security in the UK until the CP visa has actually been granted.
Best wishes
Gill