While working at Bentwaters in around 1999 I visited Woodbridge, then used by the Army for Apache training, and saw the FIDO installation which had never been removed, and is probably still there now.
Very large diameter pipes (10 - 20 inches? I can't remember) ran along each side of the whole length of the much wider runway than normal for WWII bomber operations. These fed the burners that created the flarepath. I didn't see any of the pumping equipment; maybe it had gone.
It was clear that the system would have used thousands of gallons of gasoline for each minute of operation. At least i think it was gasoline.
My father, a Lancaster pilot, said that others told him that landing while the FIDO was burning was more terrifying than stooging about over Berlin waiting to bomb, and I can easily imagine that it would be, especially with a damaged aircraft.
On the other hand, it worked; the flames would act as a guide, and the heat dispersed the fog just enough to enable the pilot to see where the runway was and touch down, with enormous care to maintain direction on the centreline.