I did it the other way around (Australian born, married a Brit settled in the UK) and I think the most important thing is to give it time. I had lived in the UK for about six years plus before I 'settled in'. I've never had the group of friends I have in Australia, but I do have some fantastic friends in the UK, and I'll be sad to leave them when we move to Australia. That said, I've lived in London the whole time, and it is notoriously transient, and and very cliquey - natives tend to stick with the people they know rather than welcoming newcomers. Many of my friends that have lived here over the years have said that. I think it would have been different if we'd lived elsewhere. Where I live, I only know my next door neighbour (on one side) and a few people to say hello to at the gym. I've lived here over 10 years.
I've tended to make friends through work and study. I can't stress enough the need to work with people you like - that's the only way to make friends in that setting. I've contracted and had permanent jobs, and I've always met more people and got more friendships out of contracting. Join sports clubs, do night courses like art, music, whatever you're in to.
In terms of the inequality of UK family vs Australia family, you have to think of it as an even thing e.g. I've lived in the UK for 15 years. In that time my family have seen me eight times. If you move, it will be the same, but the other way. I think it depends on the individual families involved.
You'll be fine, just give it a fair go. Moving to another country is a little scary, you lose your comfort zone, its a bit disorienting but it is worth it.