As far as being a Brisbane boy, Perth is a ridiculously long way from home. That said, I love Perth. Great place, good beaches, food and places to see. The mining boom has ruined things for anyone outside the industry (luckily enough I am smack bang in the middle of it, so yay for me!). I do the Perth-Brisbane flight at least once per month, and if you book ahead its really only a $600 return trip, but 10hrs of your life you don't get back(return trip).
Ponky is spot on, lots of Pommie ex-pats in the north of Perth around Joondalup, you will feel right at home there. Unfortunately most of them support Liverpool and ManUre as someone else has mentioned. As you've probably already found, there are plenty of good footballers to come out of Perth, so your kids will be right on that front. Unfortunately the Perth A-League team is coached by Ian Ferguson, but we are happy for you to join the Brisbane Roar bandwagon for a proper footballing team.
Good luck!