I have chuntered about BBC weather forecast inaccuracies since my early 20s - so it isn't just a grumpy old man thing (now I qualify!).

I do look at the BBC forecast on TV or via my phone app, but with little confidence. It may be that in some parts of the country the topography or local micro-climates make any forecasting harder - but the BBC often gets it wrong, or as the OP said it radically changes it's forecast at the last moment, just before previously unpredicted weather hits.

In lists of most accurate UK weather apps the BBC is usually shown down in 6th/7th/8th place of the most popular. Dark Sky or AccuWeather have been top of the list for a while. WeatherRadar is often good, and the Met Office's own app scores higher than the BBC.