Hmmmm, after having another look over the keys i'm unsure as to why I made my inital ID. I've contacted Dr Dirk Albach, who is very knowledgable with this genus, hopefully he'll be able to enlighten us.
Michael, here was the response I got, I guess i'll just leave this in unidentifed then.
@onetapir The plant does look like a Veronica, I admit, but V. grosseserrata has different leaves, truncate base and more strongly serrate. Also other species of Veronica from Australia have different leaves, so I would try to see whether it can be something else than Veronica.