I have feeling that Melb would be too cold and also too dry. Peanuts are a wet season crop up here - they like the constant rain for 3 months. Although they might grow in a hot house or if you have a good irrigation - Nothing to lose from trying!
Given that not a lot grows during the wet season up here I thought that I'd give peanuts a go. They are great for the soil as they put nitrogen in (like all legumes). I did cheat and get a seedling from a nursery - although apparently you can just plant a nut and it will grow! I've got another month before I pull the plants up and see if I have any nuts. Really looking forward to it!!