Hi Bezza - I definately feel your pain! I think its unfair that your husband won't even discuss the subject though, you have to have open communication with this issue (even if you do go round in circles like we do!).
You have a child so you need your family around you more than ever, you are the Mother & you need support. One thing I have learnt in our situation is that you have to take care of your own mental health & state of mind because no one else can do it for you so be careful that the feeling of isolation doesn't go on for too long. How old is your child? I think the best time for you to go back to the UK is before they start school. Can your partner compromise on your child doing school in UK then moving back to Oz after that? as you said you'd be happy to live in Oz at a later stage? That's the only fair thing to do.
I know what you mean about the half a year here & there - it would never work, the logistics of finding work all the time & kids going to school.
We've not come to any decisions yet, its been a very hard couple of months for us discussing it (although we have many times over the years) we've come to a bit of a dead end with discussions at the moment, as I'm sure you know too well.
I skyped the women in my family last night (Mum, cousin, Aunty) they were all together having lunch and it was nice to have a laugh over the phone but I just couldn't help feeling how ridiculous it was that I wasn't there & was here, feeling lonely - it felt very wrong!
I hope that you can have some more dialogue with your husband soon, its VERY important that you do. If you don't feel like talking, write it all down in a letter, as silly as that sounds it can be a great way of expressing how you feel without your emotions getting in the way of your side of things.
Sometimes I do think it's unreasonable that our partners don't offer to come to the UK for the sake of our relationships and at the same time what can you do? you love them & don't want the relationship to break up because they are the person you intend spending your life with - I feel like scrunching up our situation and throwing it in the "too hard basket".....