The philosophy in the UK tends to be different (I'm assuming that you are a GA pilot) in that it's expected that you gather the information and self-brief, rather than be briefed as is the default in the USA.
This is more time consuming and less convenient; on the other hand you could make a reasonable case that it gives you better weather situational awareness than the US system tends to give.
The default data source is the Met Office at
Met Office: Online services - customer login, but you do need to register for it. Another good source that I like using is Weatherweb at
Aviation weather forecasts
But it will remain the case that you do need to do more work for your weather data preparation than in the USA.
If you want something to really get annoyed about, try the UK NOTAM system!
G