A traveling companion and I are flying UA on a TATL flight to LHR (arriving at T2, of course) around 11:15am on a Wednesday in mid January, and then we are looking to book a flight on BA from LHR to EDI later that afternoon (departing from T5, of course). I was just looking at the BA website, and I noticed that they have an 'Economy Plus' option which seems to allow for FCOD. Is that correct? We would prefer to take the flight that departs at 13:50, but I'm not sure if we'll clear immigration, collect bags, transfer to T5, recheck bags, clear security, and make it to the gate in time. If I book the 13:50 flight in Economy Plus, will we be able to change to the 16:40 flight if need be, and is that change free? It looks like this can be done the day of departure, up until 1 hour before departure. Is that correct? I'm assuming this doesn't require any sort of payment for fare difference to the new flight, right? As it is right now, the 13:50 flight is roughtly half the cost of the 16:40 flight, so I'd rather pay for that one, of course. Would this work for me? Or is there a catch to this that I'm unaware of?