Agreed, Denham is good and The Pilot Centre is a friendly enough place, although their availability on the PA28 fleet is quite tight in the summer.
As for the FISO service at Elstree. Its a small box with an even smaller man in it. Not too much to worry about really, just give him the minimum required RT calls for ground movements. Otherwise, its "at your discretion" and don't let him make you think otherwise....!
