If you are making a child's birthday cake that requires liquorice straps then I hope this post is of use to you. I've just been able to purchase Darrell Lea Liquorice Straps at Coles. You might need to visit a large Coles store for them though. When I was about to give up on finding liquorice straps, I thought about using black, ready-to-roll icing as an alternative. It would have worked well for my particular cake.
Hope your cake turns out splendid :-)
Darrell Lea Liquorice Straps are available from Coles