Lounge access is to the F lounges at MEL and LHR for you and 1 guest, and the J lounges at FCO and DUB. You are also eligible to use the MB spa as WP flying Y at LHR T4 departure, but your wife is not. However you could use the BA arrivals lounge at LHR T4 upon arrival and transfer landside to T1. The MB spa in the arrivals is less diligent in checking status and your wife might be able to get a massage there, though it usually isn't worth the wait. The BA Arrivals lounge also serves a hot breakfast which is fairly nice and you are entitled to access as WP. Arrivals lounge at T4 is outside customs to the right -- quite easy to find. If you have over 2 hours connecting time then worth going to the arrivals lounge instead of staying in transit.