I emailed BA as I am working on another international trip via Heathrow next summer. MCO may go back on the summer schedule based upon Gatwick traffic and demand for additional seats. Nothing is set in stone, but at this time, it looks to be all Gatwick. If that is the case I am going to depart out of MIA. There will be a train that connects MCO to Miami. May be an alternative for future flights, if OP can handle additional time and travel for Heathrow flights.