Best method I've found to nail the canal bend is to follow the western edge of Watford down until you hit the sticky-outy bit that leads into Rickmansworth. Bit extreme that, though, esp. if you are coming from the W/SW.
Or you can work out the radial ('bout 135, IIRC) off Bovingdon.
I failed to spot it on one occasion last year and I would describe myself as a reasonably seasoned Elstree-ette.
If you manage to find the nice, friendly people, Elstree makes a perfectly OK home field. Unfortunately, the visitors only experience the worst aspects (see above) of the place most of the time.