If the perp was the one who was sending flowers to her home address, then he did know where she lived. Parking her car there would have suggested she had gone home for some reason, or been abducted from there, either of which would indeed have been helpful blind alleys. If her mother was to be believed (far from certain), she needed to go home for her tennis gear.
In either case, Disraeli Road or Stevenage, the question arises of where the perp went from there after ditching the car. Everything about what happened outside 123SR is inconclusive - when the car appeared, who was around, and so on.