Dorara, Even if LHR/FCO x 2 both cancelled, BA is also flying to Milan or (if you really do need to get there) there are also Ryanair flights to Ciampino and to other Italian cities. Train from Milan or any Ryanair destination to Rome is easy. So if there's a second wave of COVID, you may be unlucky but if it's merely LHR/FCO cancellations for operational reasons (which is unlikely), there are still plenty of other ways of reaching Rome.