All a moot point, I ended up booking a 6hr layover over a 2hr one, which would've been fine except our Emirates A380 flight from LHR was cancelled as the aircraft was involved in an accident with the catering truck. So 6hrs turned into 12+hrs plus overnight and a .... fight to rebook during peak season.

Probably couldn't do this within two hours, as the Emirates lounge ended up paging me to confirm the baggage. As a UK citizen with QF Gold, passport control and Fast Track security were great and very quick anyway at T3.