Firstly 1987 is a long way back in terms of computer weather models.
Secondly I don't think the Met Office consists of one man (or woman) who stands up in front of the BBC TV camera. In fact some of the present-day BBC presenters look like they might be more comfortable selling lottery tickets. There is a lot of work behind the scenes involving a lot of people. They also look at models produced abroad to see how they compare.
Fast moving / extreme weather is very hard to forecast. One can occassionally find big differences in the data from the UKMO, and the U.S. run GFS model (e.g.
here) which most of the world runs on.
As to the conditions (actual or forecast) which a school will fly on (
dual assumed) one could debate this both ways. An honest instructor might not wish to waste the student's money flying in bad weather. I also know many instructors do take people up in bad weather; one sees this every day when flying. IMHO, if you take up a fresh student for circuits in 15kt crosswinds his money will be largely wasted, but again this could be argued both ways.
For
solo flight when self fly hiring, it's up to the school where (in terms of weather) they set the rules. If pre-PPL solo, the instructor doesn't want a blot on his license by sending up a student against a bad TAF which looks unreal but which later turns out to have been correct; he won't have a leg to stand on if that happens.