Re #48 MilesMagister - We do still have a copy of the big yellow book 'Airport Weather Characteristics' if you're passing through EGNS (with thanks to Dash&Thump #8 for comments on TAFs/METARs)
Re #42 I agree with the detailed analysis SIGMETnil - as FullWing says in #47 there are parameters for introducing change groups in TAFs (and TRENDs) - but you don't have to pay £75 to download ICAO Annex 3 since all of the info is freely available in UK AIP GEN3.5 at
http://www.nats-uk.ead-it.com/aip/cu...GEN_3_5_en.pdf