Sorry @Charlie m, I had a look at some of your other posts and I think I see what you're asking.
You want to come to Australia and then apply for a parent visa onshore, yes? In that case, you apply for an ordinary tourist visa, the same as if you're coming on holiday.
A day or two after you arrive in Australia, you apply for the parent visa. Your tourist visa will remain valid. They will then grant you a bridging visa while you wait in the queue.
You may already be aware of all the restrictions of living in Australia on the bridging visa, but just in case:
You are not allowed to leave Australia, even on holiday. If you want to leave the country at any time, you must apply for permission (called a BVB), and explain why you need to go. The application can take a while to process so it's vital to plan any travel well in advance.
If you want to buy a home to live in, you will have to apply for special permission from the FIRB (Foreign Investment Review Board). The fee is a few thousand dollars. Then you will be charged up to three times the usual stamp duty on the house purchase. This can easily add $50,000 to the cost of buying a home.
If you're receiving a British government pension, it will be frozen at today's rate - you will never receive any increases or additional benefits. You also won't be eligible for any Australian government support because on a bridging visa, you're legally classed as a "non-resident".