I have thought about this a bit before, as I know 3 or 4 women who have (adult) children who moved to Australia and NZ, and one woman who has TWO children who moved far away; one to Oz and one to Chile! I have no idea why, as neither of them has a spouse from those countries. They are British!
I would be gutted. I wouldn't say that to them, but I would be gutted. I am not getting any younger, and me and DH are not rich, so we would probably never be able to go and visit them, and would rarely get to see them. I would also be upset at the thought of my grandkids being 12,000 miles away and us not getting to know one another. As a number of posters have said, it is a VERY long way away, and visiting regularly is not on the cards for most people.
I have also seen several programmes where people move to Oz and NZ, and on many occasions, they regret it. And it's very hard to undo things once they have gone through with emigrating, and is especially hard if they have children who are born there, because it can cause problems if they want to return to the UK.
One story was about a woman who met an Australian man, moved to Oz, and got married to him, and had 2 kids with him. All within 3-4 years.
When the kids were 3 and 5, the marriage broke down, and she wanted to come back to the UK as she was very low and upset, and needed her family. But because the kids had been born in Oz, and their father was Australian, she had no right to take them to the UK. They were Australian, and the only way she could take them was if her husband gave his permission, and he said no.
So the only choices she had were to go back to the UK without her kids, OR stay in Australia. Awful really. I think she stayed in the end, but this was 4-5 years ago. I don't know what happened in the months/years afterwards.
Another thing is, I know a few people who were qualified as plumbers, and other tradesmen, and nurses and teachers, and so on. They moved to Oz, and had to retrain for all their rules and regulations and shit. Takes about an extra year, and you don't get paid while you're doing it. You also cannot work while you're doing it, as the training takes all your time.
So you literally need enough money to live on for a whole year; like 45-50 grand (GBP,) or so. And that's not including the moving costs and air fares etc, which can add another 10 grand on. And properties in decent parts of Oz cost a FORTUNE.
Me personally, there isn't enough money in the world that you could pay me to move to Oz. I think it's massively over-rated to be honest. I would visit, (if I got a free holiday,) but live there? No way. It's not even in my top 20 places I want to go to. It's too far away from the rest of the world, and it's too hot, and most of it is a dustbowl, and there are too many dangerous insects and snakes and suchlike, and it's expensive to live there.
Re the OP, fortunately, my 2 adult children never have any intention of leaving this country. Thank God.