After talking to a friend I've found out it's called Thalaina clara or Clara's Satin Moth from the Geometridae family (due to it's geometric markings). They like feeding on Wattle trees during their caterpillar stage, have a wingspan of approx 50mm when they are adults.
I thought the markings on it's wings were quite unusual so I took a photo as I wanted to sketch it and wasn't sure how long it would stay still for. It was fairly dark and the autoflash came on which showed up the reflective orange colour in the middle of each line. Just looking at it quickly I would never have noticed, without the reflection it's a very dark colour (and quite small) so I just passed it off as a really pretty white and black moth.