bear in mind it's only a guide and not 'official'.
No such thing as "official".
What you may see is weather sources mentioned in the CAA "safety" leaflets - most of that stuff, and most present day PPL and JAA IR training is still pre-internet. These sources are not in any way legally required, though some people might want you to think so.
What you also get is AOC operators whose pilots are possibly required to brief as per the company manual, and indeed there are specific guidelines there for e.g. disregarding PROB30 TEMPO etc conditions (unless persistent e.g. fog).
But for private pilots, "official weather" is 100.000% BUNK.
It's time the GA scene dragged itself into the 20th century and used the internet.
Today was a case in point. The F215 contained everything including the kitchen sink (it always does; I don't use it) and scared off most people. But a look at the radar picture (e.g. meteox.com) made it obvious that it would not be happening at the apparent speed, and there was little real convective weather there. And later TAFs showed plenty decent enough cloudbases for VFR flight.
The forecasters always chuck in the kitchen sink (they get 100000 old ladies on the phone if they don't, complaining their daffodils were ruined by an unforecast shower) but pilots needs to use modern sources to get a
local supplement to the forecasts.