Just addressing your points:
Pro 1 - Where are you looking to buy in Australia and UK, as I find it strange you can afford a decent sized property with low mortgage in UK, but can’t do the same in Australia? Not sure you’d get a mortgage in UK without employment, so you may end up renting a while too.
Pro 2 - We moved to Australia with no children, then had twins. Not having my family was tough (although they were here visiting when the children were born), but I was lucky as my parents (and later my brother) moved to Australia and we all live within a 5 - 10 minutes walk of each other. I feel a massive pull back to the UK because of my extended family and friends, but because my immediate family is here I am happy to stay in the (waaaaay too hot in summer) sun. Your family may not help with childcare/babysitting. You say you have close friends, can they not babysit on rare occasions so you can have a date night (find it strange they haven’t offered if they are close)?
Pro 3 - Don’t using your holidays for visiting the UK - holiday where you want to. When we first came out we holidayed everywhere except the UK. We still do a yearly trip, but it’s normally just a stop for a rest between places we want to visit (we usually buy a round the world ticket- cheaper to go three or four stops than ever before). We are happy for people to visit us in Australia, but plan it so that my husband doesn’t have to take the entire time off. So they’ll come for say a week, then we’ll book a trip to Gold Coast/Sunshine Coast where my husband will come for a long weekend then fly back to work, then we’ll stay there for rest of week, then back home for a week, then another trip elsewhere - Sydney/Melbourne etc - husband does long weekend then back to work, I stay with friends away, then back home. That way my husband doesn’t miss too much work and our friends/family get to see different parts of Australia.
Cons 1 - You’d miss your Australian friends, but I’m not sure how close/great they are if you aren’t comfortable enough to ask for one night of babysitting. You might pick up with old UK friends, you might make new ones - you won’t know until you move back.
Cons 2 - Get jobs before you move back. No point moving without a job lined up as any savings will be gone very quickly. You’ll also need employment to get a mortgage if you wish to buy a house.
Cons 3 - Australian health insurance is pretty good, but you a lot pay for it. You can also get private health insurance in the UK.
If you do decide to move back I would wait until after Brexit to see what happens to the economy and house prices etc (possibly nothing, but I’d still wait).
Remember the grass is not always greener (although I guess it is pretty green in the UK 😬)