You poor love, I feel so sorry for you. :(
I too am married to an Aussie - he also said that he would expect to move back to Australia when we were married and I agreed to it, rather less reluctantly than you by the sound of it but still with levels of doubt.
But! DH has a very good job here, we live in a nice house that his mum owns but we pay her rent for, it's much bigger than the house I own in the UK and bigger than anything we could afford in the UK, so already we're several steps ahead of you there.
I don't work at the moment because I left behind 2 jobs in the UK, neither of which would be easy to reproduce here (one was client-based self-employment, which I can pick up when DS2 goes to school in 3 1/2 years time and the other, no chance) and it was pretty much part of our "agreement" that I could stay at home with DS1, who was 20mo when we moved out here, and any subsequent children.
We put an initial time limit of 3 years on it - if by the end of 3 years I hadn't adjusted, completely hated it and had to go back, then DH might have reconsidered but it would have half killed him to leave his mother
and all the stuff he loves about Australia. As it is, after 3 years I was ok to stay and in all honesty I think I would have needed a barrage of reasons, not least being my health, to have forced him to return to the UK.
I go back to the UK every year with the DC (but not DH) - I see my friends and family when I return and in between I skype my Dad and my sister and any friends who want to. Every time I go back I wish I still lived there, I still miss it - but now I miss things about Australia when I'm there too and so does DS1 (DS2 still too small to notice). We have friends here, DH has the good job, we do ok - DS1 is in school and has lots of friends and his life is really here. I too feel guilty about my family missing out on the boys growing up but Skype really helps to keep them in touch, and DS2 loves to see "Bampa" on Skype whenever I'm talking to my Dad, he followed him around like a little tail when we were over there at Easter! But that makes me sad again too - I so wish Australia were nearer to the UK! :(
DH and I don't have the greatest of relationships - he annoys the shit out of me sometimes, especially when he's pulling the "typical Aussie male" crap - but we get on well enough and I don't think I could leave even if things did deteriorate because of the sodding Hague convention.
So that's my situation - but yours is slightly different. I think you should take the children and return to the UK under the circs - your H then has a choice as to whether or not he joins you. But as he's currently not really supporting your family in any useful way (if he was a SAHD that might be different - at least you'd save on childcare costs!) then you have to do what is best for you and your DC and that, as things stand, seems to be to go back.
Where are you based? If you're near Sydney, we do have a MN group of expats who meet up every now and then - we're very nice, I promise!