Hi,
If you are settled (and the children) and have good family and friends around, then be at peace that you have made the right decision. It is a huge move, maybe if you need a change of scenery you can change something closer to you (i.e. holiday, change of routine etc) and appreciate what you have.
I am English, but moved to my partners country, and now to Sydney. I love Sydney, but I think that is mainly because I was so happy to leave where I was before and culturally it was much more similar to England, but with 3 little children I have the need to be 'settled', and as I get older I am more and more concerned I may never find it, if you are happy with daily life then I would stay put. I seem to get through the stages of emigration, but never end up feeling at 'home', I think that even if we came to England I'm not sure I would now as I have been away so long and picked up little things from Sydney and Norway.
Once you have children the main importance seems to be daily life and if you have it sorted it will take time to get sorted in another country. Of course if you wanted to you, I'd say go for it, but if your hearts not in it, thats ok.
If you do come out here, schools not a worry (at least primary), schools are of a high standard (an aussie friend recently moved back to Sydney from London and her child, who was top of the class in the UK, was put straight back into the reading recovery program here), High school is different, here in the eastern suburbs all the primary schools in my area (and if you're in area you automatically get a place) but no one is sending to public high schools, and all have been on the list for private high schools since age 2, and they are all single sex. I've put my head in the sand with that one, presuming we won't still be here.
Daycare can be tricky, 2 yr lists where I am, about $100 for long daycare (rebate is up to a certain amount, so doesn't work out to be 50%, or $54 for preschool where we are (no one gets rebate) and school hours and term times.
We just got PR, so now entitled to child care rebate, but loose LAFHA so actually worse off (just when I though it would get easier!) - its super expensive here ...
I sometimes wish I had just stayed home (10yrs ago) and now would be happily settled with good friends, secure job, feeling at home, but there will always be a parallel life and 'what if's' its for you to decide what works best for you.
Good luck :)