Hi there,
Cannot speak for your law degree but we have been here 5 weeks, me my husband and 3 girls.
There is work here albeit they slow down coming up to Christmas so tradies will need to budget for that in the year. My other half does have work and luckily have found a job that pays brilliantly. No guarantees that it will last though so it's a case of proving yourself to be reliable, produce great work and having your own kit helps too. Working with a gang pays less I have been told. You have to get yourself out there and chat to people, go up to people building and ask them.
Save up for the kit here too, it's very expensive my husband says the bell cement mixers here are double what they are in the UK but we didn't bring ours as we thought it wouldn't get through customs. So brickies put aside a couple of thousand ($) for kit I would say to include a trailer if you're not going to get a Ute.
Gumtree Perth is big here for everything for sale and jobs, there are always adverts for tradies on there. Also The West Australian is the largest if not only paper here that serves Perth and has jobs in that too. Check it all out online.
Brickie rates start at $250 per day and can go up to $350+ depending on who you are working with.
and for all of those people that say you can only get by with bringing a bit of money over here -WRONG! For a family of 5 I would say you need to bring over about $30,000 at least if you're starting over.
Saying that these are the things to watch out for but Perth is fantastic. Glorious weather, friendly people, beaches close by (we used to live 1.5h away from Bournemouth) and here it's 10 mins. We love it!
HTH and good luck with your plans :-)