Don't think it would be a problem for your dh to get a job, depending on how flexible he is willing to be. Actually my sister moved into IT there never having had anything to do with it before. She did say it wouldn't have been possible if she had not by then got an Australian passport mind. She is married to an Australian so was able to do that. She did say the passport made a big difference re job opportunities generally.
Can't advise about transitioning back. Schools seem good, nice facilities. She sends her 3 to a pvt school but says after all 3 were there, a new state school opened up just a short walk from her home with fabulous facilities and actually they would have been fine there. Don't know how the systems compare but you could supplement (time and inclination permitting) what they do with a few UK workbooks just to be sure the transition back is smooth.
Seem to be endless activities available. You name it, my nieces do it and my sister is ferrying them about all the time from one thing to the next (drama, ballet, music, swimming, fencing, various sociable girly get-together activities). They are all fantastic swimmers (naturally enough), swimming is big there obviously. Summer is very hot and the dc are out a lot, even in winter.
My sister had no problems meeting people there but her dh is a local so his family were there and since he went to school there, he knew his way around and that may have made a difference. IME generally Ozzies are not stand-offish people. Whether you'll click with them or not, I can't say but they are not forbidding or unapproachable.
Certainly coming from Germany, I did find it a very chatty, friendly type of place. I couldn't go anywhere without people coming up and starting to chat (men, women, old, young), found it pleasant and not too over-powering. So on that superficial level, it's easy to be sociable. I don't know how it is with real friendships. Took my sister some time I think to meet people she was on a wave-length with at a deeper level