Hi,

We are travelling from BCN-LHR-HKG on a single ticket, first leg is BA to T5, then CX from T3. Do we need to go through passport control and come out of T5 and then go back in through security etc in T3? What about checked luggage, will that go all the way through or do we need to pick up in T5 and manually move across to T3? Lastly, what is the best way to get to T3, is it tube?

We haven't changed terminals/carriers like this before so apologies if these are rather basic questions!
Thanks