Has anyone done Option 3 and have a rough idea of how long it takes? I am coming off QF1 in T3 and then need to do a B2B LHR - OSL - LHR for the last leg of an exEU. I have arranged for AirPortr to in T3 arrivals to take my bag home while I go to OSL. Arrive 06:50 and then depart T5 12:35, so plenty of time between terminals.
BA cancelled a LHR - OSL flight after I booked, so my perfectly timed connections are less so. If I am over flying by then (LHR - ARN - LHR - DXB - MEL - SYD - WTB - SYD - DXB - LHR), I may go the opposite way on the Tube and head home.