Its been a while since i worked there so i stand to be corrected by someone still there BUT no one from an ATC point of view WANTS to LVP's, they are pretty much a nightmare wherever you work, particularly at LHR-and I would venture to suggest that going LVP's would exacerbate any staff shortage situation not help it, certainly from a tower point of view.
As for instigating them early, this is probably down to the fact that it takes so damn long to bring them into force at LHR. Yes 200 ft cloudbase is still inside CAT 1 minima, but it only has to fall slightly and CAT 111 protection will be required; if you wanted CAR 111 protection how would you feel if you were told it would take 45 mins to give it to you???
Not only that but until recently only one of the runways was CAT111 capable meaning that not only did the airfield have to be protected but an alternation had to be orgainised...not something that can be done at the drop of the hat....correct me if i'm wrong but AMS/FRA do not have such restictions and have more runways and concrete to play with??