It’s often the case the multi city will be cheaper, and will bring up better connections than the default option owing to limitations in the booking engine, while google flights shows cheaper multi city option using multiple airlines.

Open to non residents only, the Qantas Explorer Pass is also often a good option https://www.qantas.com/gb/en/book-a-...-explorer.html, Virgin 2.0 doesn’t offer similar at this stage. Another option is to keep an eye on happy hour sales every Thursday 4-11PM AEST https://specials.virginaustralia.com/au/sale/happy-hour, they frequently have specials that cover holiday periods.