I completely agree re unreliability of forecasts, but I have had no success in complaining to the Met Office, who respond by saying there have only been X occasions when Amended TAFs have been issued as a result of METARs exceeding the TAF parameters by specified amounts. I believe a significant part of the problem is that, without Met observers, the Met Office machine is now particularly bad at estimating changes which make the difference between VFR flight being possible and impossible, such as cloudbase changes in the 1500-2500 height band.
But you do have to be careful about presenting any such case. In the EGPF example above, it wasn't 2 hours between the two TAFs as JW implies, it was nearly six hours, i.e. the normal TAF cycle, and the only significant things missing from the actual weather in the intervening period were the forecast increase in wind strength and the TEMPO 3000 RA BKN005. My guess, looking at the progress of the weather (esp the bands of heavy rain) across central Scotland this morning, is that the absence of same at EGPF was a matter of a few miles difference in exactly where those bands tracked through the Glasgow area.
NS