The BA premium sale prices are pretty competitive. Just returned from Sydney having got First for just over £5K rtn. I have found CPH as a good starting point for fares Especially to USA. Recently saved around £1500 for a CW return to Boston out Monday, back Thursday. But it’s a bit of a lottery as to what’s on offer at the time.
Btw if you do go BA try and get on the Qantas A380. VERY impressed. Though also got new first with BA on SYD / SIN …… Classy!