I did it last month - you get fasttrack - I was first one through from the flight, no other longhaul widebodies apparently arriving, and it took me 1 minute. I was not in transit, but same process.
The flight was late due Thunderstorms when leaving LHR, so everyone heading to Bali missed their connection - no great issue as there is a later connection and everyone going on to Bali was met from the gate.
Enjoy your flight - I had a great one, considering a Trip Report!