However every time he has suggested returning, he has always agreed to stay in the UK for a few more years.
it sounds like he was asking before you had children and if that’s the case it would be a quite unfair for you to use the children as a reason not to move back now, besides if they haven’t started school yet, it’s the perfect time to move them, they’d settle again and make new friends.
me personally I’d be weighing things up VERY carefully, a lot has changed in the last few years and that is as good a reason as any to open a dialogue on any doubt you now have, but you should probably try and get to the bottom of what is really bothering you about the move before you discuss it further, hopefully he’s willing to sit down and weigh it up completely.
but, ultimately, I’d be asking, can the children have a better life over there? If so, will that be enough to cast aside any doubts you have? I’ve got a two year old and I feel really quite apprehensive about the uk that she’s going to grow up in, but we live in a shit area, we’re planning on moving to a nicer area before she starts school, but everything is hard and getting harder here, no matter where you are.. no idea what it’s like in Australia though!
good luck OP, it’s a difficult problem to negotiate.