Thank you to everyone who has replied to my post. I have to say WOW, it seems that there is so much more involved in moving to Australia than our son thinks there is and even ourselves.
It is something that is going to need so much more research and thinking about before even making some sort of decsion about what myself and wife should do. The financial side of things for visa's is huge, also the long waiting lists and this would hit our finances very hard and that is not something that you want at the moment with everyday living costs going through the roof.
Losing all that we have here in the UK, other family members, friends a nice home, our jobs, would be hard to give up. Then there is the chance that just because our son and partner have settled in Australia, we may not find it so easy, despite them being there, the tug of the UK maybe to much to give up. As has been suggested in the comments it maybe better for us to just visit for holidays.