Thank you all for taking the time to reply. Have had an amazing couple of days in Tokyo, and am now sitting in the QF lounge at NRT. Lines at both security & emigration were pretty short, so no problems. In fact, security reminded me of how it used to be, friendly staff and no major fuss.

I asked at check-in about lounge access, and the agent told me she though I could only access the QF lounge. Check-in was pretty funny actually. I have a connecting flight from SYD - MEL after I land, bought on a separate ticket. When I told her this she appeared confused at first, and then called over a colleague. Eventually there were four(!) of them crowded around her monitor debating my situation in Japanese. After about 5 minutes I asked if there was a problem, and the agent smiled and said everything was fine. About 5 minutes after that, she printed off my luggage label and boarding passes for both flights. Quite amusing - there were still three of them there when I left the desk.