He could get a job anywhere in Australia as long as he was sponsored by an employer.
There's a lot of negativity on this forum re:457. And it's not easy, because you are always looking over your shoulder in case you get made redundant. BUT. You're in your 40's, your kids are practically adults, this is your time. Go for it. Take a risk. You never know what will happen in life and at least you'll have tried.
My hubby & I and my 15 year old step son came over almost 5 years ago on a 457. We were in a very precarious industry and a few times we thought we'd have to go back to the UK. However, we got PR in 2013 and then on 26 Jan this year I became a citizen (just applied for my Oz passport!). So it can work out. Just to add a bit of balance to the "got made redundant, had to go home" stories.