Note that if travelling on Cathay Pacific (or any other OneWorld Airline) in Business Class or First Class you can access any OneWorld Business Class or First Class lounge (according to ticketed cabin) that is available in the departure terminal. So if in Business on CX, you can access the Qantas Business Class Lounge and if in First Class on CX you can access the Qantas First Class Lounge, regardless of FF status or Qantas Club membership.
But if travelling on CX in economy, then a Qantas Club member without OneWorld Sapphire or Emerald status cannot access any Qantas Club or CX lounges.