Take a peek at this article. Your leaves look like a disease here called Early Blight. I have no idea if it is endimic to Australia. Sorry I couldn't isolate just that part of the article.
hortster

Here is a link that might be useful: Tomato diseases

hmm, i thought it mite be that. I am spraying with copper sulphide spray, but i think it's too late now, once the leaves show? I have had this for a few seasons, and i try n keep plants healthy for as long as i can - using coffee grounds from my local cafe seems to give the plants a lift too. now it's autumn (fall) here, and i have plants still setting fruit, so i hope to try n keep the fruit set ahead of the disease. any tips to minimise it's affects would be great too.

thanks for your help mate.