What does the 3 day forecast look like?
You can get the UKMO MSLP charts for free, from sites such as
this. Not as ordered as from
Avbrief (which presents the latest ones and nicely up to date etc) but usable.
You can also get weather from the GFS weather model from e.g.
here and frankly I do not believe anybody can get better data for 3+ days ahead, for which most forecasts are either pretty obvious, or pure imagination, or anything in between
There is a fantastic range of free weather sites. I have not used the UKMO site ever, in the 11 years since getting my PPL. Well, I use it for the
IR image (high altitude cloud tops) but even that is available elsewhere, just 15 mins delayed.
At aviation shows I have often suggested improvements to the UK MO man but his reply is always that they cannot offer this or that because they have to make money.