moogsonskates, You have ample connection time, and very good advice from
Microwave.
Just follow the Flight Connections signs.
Get your BA bp asap, whatever that means in practice: online yourself, AA check-in agent in MIA, some BA/transfer desk at LHR etc. However tis is just a matter of convenience, not a do or die deal.
In practice, your greatest time-waster is likely to be the T5 security line if you forget to separate some toothpaste or shampoo or mouthwash bottle from the carry-on. Take care of that, and you'll be fine.
