There is availability :
F 9/26(FR) UA100 San Francisco Washington,D.C.(IAD) 12:45 20:56 752
F 9/26(FR) UA924 Washington,D.C.(IAD) London(LHR) 21:41 10:00+1 777
C 9/27(SA) BD054 London(LHR) Edinburgh 11:05 12:30 319
or
C 9/27(SA) BD056 London(LHR) Edinburgh 12:50 14:15 ER4
and also on a couple of earlier departures from SFO on the same day on the same route, only these are C in SFO-IAD and F IAD-LHR.
What with the FCT on the way out, thats you sorted then.