I have used the QF lounge at Brisbane when flying with EK in J - in fact when I spoke to the EK lounge about the fact that I had been waiting a couple of hours for them to open the doors I was told that I could use the QF lounge when the EK one was not open. Therefore could the OP not use the QF lounge until it closes at midnight, by which time the EK lounge should be open for the 0235 flight?