Something we discovered quite by accident is that we pay more for airfares from Australia to the UK than you pay if you're in the UK and travelling to Australia.
The planning for our trip last year started with me booking a tickets to go to Germany, then to London, then home. Mick said he wouldn't come as he doesn't get paid any annual leave but we wanted to learn more about boats for sale. I wanted to see my German friend who is going through a tough time so I went ahead and made the booking. Over the next few weeks Mick started saying more and more that he wanted to come too. I kept saying I'd book him tickets but he'd say "No, we'll save the money". Eventually I got so tired of the "wish I was coming" that I just told him I was booking. But... by then he couldn't get on the same flight as me so said he'd skip Germany and just meet me in London.
I had enough frequent flyers for one way so we only had to pay for the other direction. I checked the prices and schedules each way and much to our amazement there was a huge difference which way we booked it. The frequent flyer point cost was the same either way, but we saved more than $400 by paying for the ticket from London back to Melbourne.
I just did a quick comparison of Qantas fares on September 14 and returning September 28 - just out of curiosity, not because we are planning on going anywhere! A return fare from Melbourne to London and back was $2,228 but the same dates from London to Melbourne and return was GBP 1,056 which is something like $500 less.
So, we'll be keeping this in mind when we get over to the UK. If we want to come back to Australia to "visit" we need to check carefully, especially if we can partly use frequent flyer points.