This is a really tough situation.
Asking your partner to relocate goes way, way beyond a mere "compromise."
My comments come as the child of a diplomat who moved frequently. By the time I was 12, I had lived on three continents.
As an adult, I've lived and worked in four different countries. In addition, my husband and I have different nationalities. We lived in his country for seven years, but have now relocated to the UK, where neither of us are from originally.
I'm very close to my siblings and their spouses, but we live in four countries scattered all over the globe, and our children have never met.
In short, I have relocated a lot more than most people, and probably find it a lot easier than many do. However, it's still hard. I would have loved for our children to grow up close to their cousins, and to live near my siblings.
I would say that my international relationship has worked. But I completely understand that for many others, it would be a step too far.
If you know that you don't want to live and raise a family in Australia, I would move back to the UK sooner rather than later.
Unlike some on this thread, I don't think your partner's unwillingness to emigrate makes him selfish. Everyone has a line they're not willing to cross. Having done it, although it has worked for me, I completely understand why he's not willing to try.
Hugs and
for you. It's good that both of you know your minds before it becomes even harder to go your separate ways.