If you want something active, don't get a snake. None of Australia's active snakes (and not really any in the world) are good for beginners. Almost all of Australia's highly active snakes are venomous, two are colubrids (Common Tree Snakes and Keelbacks, neither of which is suitable for a beginner). If you want a highly active reptile, go for a monitor lizard, or maybe one of the small or medium diurnal skinks. All the Australian snakes good for beginners are pythons. None of them are active.
You're definitely going to have a better time if you start with something easy, get a feel for what's involved, and then think about something more ambitious. If you really have your heart set on a highly active snake which is arboreal and not venomous, only one exists in Australia (Common Tree Snake), but understand that it's a species most beginners would struggle to keep alive long term, and having an animal fail to thrive is not a fun experience for any party involved. Tree Snakes are also not great to handle, they're more of a snake you keep like a fish. If you're a particularly keen and switched on individual, hey, don't let me stand in your way. On that thought, hey, if you want to get something venomous there are some wonderful options in the way of active snakes which are a lot of fun to keep, but they come not only with extra husbandry challenges, but also with everything involved with keeping a venomous snake, and while I don't recommend it, plenty of people handle their venomous snakes and when I was younger and more stupid I regularly freehandled deadly snakes myself.
Ask yourself why you want a snake and what you're hoping to get from the experience. If you want a snake to handle, you'd do well to start off with a Children's Python (any type) or a Carpet (more or less any type) and get a feel for what keeping snakes is like.