I take it the OP’s boyfriend is a doctor. And the OP has enough £££ of her own to be granted PR in her own right, hence didn’t get married to him before they left the U.K..
Doctors generally have far better living standards in Oz than they do in the U.K. in terms of £££ anyway. especially when they reach consultant. But they can have a great work life balance before that, compared to U.K. anyway.
I’ve known doctors and their families go for ever and some who returned after 10 years. The ones that only went for a year were only there for a specific 1 year thing tho.
OP if your boyfriend is set on doing the 4 years then you might want to consider how best to make it work.
Coming back after 1 year would likely mean redoing training he is in the middle of in Aus. Plus. There are not many jobs in the UK right now and there appear to be many Down Under.
So,,,,.. to make it work….. can you organise for your F&F to visit at regular intervals over the next 12m - 24m? Incl over Christmas.
and could you come back for a 3 week break here every British summer?
Also could you move somewhere more suitable for you and the kids?
and you really do need to adopt a granny or find a student to babysit. It does sound like you and your boyfriend need to invest in your relationship a bit more, which means getting used to other people looking after your kids. Even if it was only for a couple of hours whilst you went to the gym or out for dinner or to do a Cross Fit class….
i had a friend who was in Sydney and they adopted a granny. Was brilliant for them and their kids.