Join QF FF from the UK. As noted BA are moving all us SoPac members to QF currently anyway. You could keep BA EC if you can maintain a UK or Euro address but the QF FF is more generous than the new BA terms in any case. Only other consideration to join BA would be if you fly a lot with them and want to take advantage of online or telephone check-in , or are purchasing high revenue fares for status.

Good luck with your move to Oz!