Hi, just another point of view from another expat (I've lived in many countries around the world, and have close family in Australia who I've visited a couple of times).
Apologies to put a downer on it, but you seem to be welcoming opinions, and I only write mine thinking it might be useful to you to have more of an objective view...
I think there was a reason why, when people emigrated 100 years ago, their family in the UK held funerals for them. I understand that emotive example because, despite the relative ease and expense of travel, phone, email and skype, moving to the other side of the world effectively will end a meaningful relationship with your friends and family left in the UK. Your children will probably not have as close or meaningful relationship with their grandparents, and you with your parents.
You can't expect any visits at all. You can't expect people to pay thousands (we just paid nearly 3k for 3 people return flights to Australia on cheapest tickets available) and use up their annual holiday allowance to see you. However, because they love you and Australia is interesting, they probably will come. But maybe not as often as you anticipate, or they say they will in the initial excitement of early plans. Any visit is a bonus. And the onus to keep the relationships going, by phone or visiting, is all on you, as the person who moved away.
Skype can be very frustrating and often freezes/cuts out. Your DH may or may not be proactive in keeping up family links (making chatty calls, putting together packages of the childrens' artwork, photos of your new life, etc, remembering birthdays, planning the next trip back to the UK - which can take as much logistical planning as a Royal visit sometimes). If not it will fall to you, and if the family relationships aren't to erode too much, you have to do all this tenfold. Not to mention the guilt from your Mum, mother-in-law, who if they visit, may spend much of the visit reminding you how much they miss you and the grandchildren and taking poignant photos to cling to.
Also I think Australia is currently as expensive as the UK (especially the cities), and not the promised land some people (not you) can sometimes think it is. The outdoors life, for example, is no better than many many places in the UK. There are plenty of threads on here about the negatives of Oz...
Clearly I'm biased and cynical, as much of what I have written is, sadly, from my own experience and that of expat friends. The package you move for really, really, really has to be worth the huge sacrifices in terms of family, support and identity.
I live in continental Europe at the moment, and am luckily enjoying many of the benefits (namely financial) from being an expat with the fact of easjet and 90 min flying time making it much easier to keep family relationships going. I still find Skype a bugger, and find keeping my dc's lives running, and constantly planning trips to see grandparents takes a huge chunk of my time. My career is somewhat on the backburner, firstly for having moved for DH's career, and secondarily because it's harder to keep climbing that ladder outside your home country, and thirdly because I have less time and physical family support here.
This post is a big list of cons, and I really hope I've not offended you with any of it - absolutely discard if none of it chimes with you, and best luck with the decision.