What man doesn't agree to go back to the UK if that's where his wife wants to take the kids? Even if you don't want to be married any more you still want to be in the same country as your kids? What man would expect his ex wife to stay in a foreign country?
Coco did you read anything i wrote? None of us ever marry someone thinking they'll treat us/our DC like shit. None of us give up our own careers to support and follow someone else's thinking we're going to have to start over again in our late 30s and worried about how to get DC through uni b/c XH sure as shit ain't gonna contribute. etc etc.
Me: Canadian w/ Canadian xh on expat assignment in US with possibility for permanence. DS - i was sahm for 4 years. at time divorce was filed, XH had the opportunity to turn down the localization and be sent home to Canada with job intact but lose promotion opportunities in the US. instead, he knuckled down and refused to let me return home with DS, knowing that if we divorced there was no way i could legally stay in the US and that a court could rule DS had to stay in the US also, despite having zero interest in being primary caregiver to DS. it took me 1.5 years and $75,000 to get out. Since we left, he has only visited 4 times in 7 months - it's only a 3.5 hr flight away.
If I could have found a job that would sponsor me for a work visa, i would still be there because I believe it is in my DS' best interest to be near both his parents. I applied to 50+ jobs and I have a Masters degree in a technical field that qualifies for a NAFTA visa and still couldn't get anything. He still could come back to Canada and get a job here to be close to DS, but will never do that because his career is more important to him.
Friend 1 situation: italian national with spanish XH on expat assignment in the US. it took her THREE years to leave the US with their two DDs and $100k, despite the fact he had zero intention of permanently settling in the US, and could have requested repatriation. the XH commutes to see the DC in spain once a month.
Acquaintance situation: Australian couple with one DD on expat assignment in US - her very rich parents had to come over and pay for her divorce so she could retain custody of their DD. XH threatened her that he would take DD away and she would get deported to Australia.
Friend 2 situation: canadian married to us citizen. 2 young DS. she will likely never be able to return to Canada because he will not let the children go, and she has a green card so a judge will likely not rule in her favour since she has the ability to legally stay in the US and get a job.
I have also just thought of another situation I know of with an abusive H. H is Canadian on expat assignment in US, W is from the west indies on spouse visa. W had an older DS by a previous partner and a younger DS by this H. H abuses her financially (only puts enough gas in car to go to grocery store and back, she has no bank acct, no credit card etc). H has an OW, and threatens W that if she tries to leave, he will take both DS and sponsor the older one who isn't even his to stay and she will get deported back to the west indies.
That is not to say you should expect this to happen to you, but you should be fully aware this could happen to you and be prepared to deal with the fallout. I cannot describe to you how it feels to be stuck in extended limbo not knowing if you'll lose your child(ren) because your STBX prioritizes his career over the best interest of the child(ren).
In your situation, I would research heavily what your options are for getting your own visa to stay in Australia permanently in the event your marriage breaks down and you are unable to return to the UK with children, and what your job prospects would be like if you did indeed stay there longer than planned. I would also research family law and see where that would land you if your marriage did break down.