I usually use www.passageweather.com as a guide. They offer a 7 day forecast; which should be treated as a guide only. Weather forecasts are rarely accurate over 2 - 3 days. It's good to see a visual representation of the systems, as even if the prediction is wrong, you still get a sense of whether or not it could get rough and stormy on your particular route.
I know it's just the Met Office charts, but the reason I liked this site was that each chart filled the screen with no logos, adverts etc. competing for screen space, and I found it much easier to read. I'll just have to get the information somewhere else now!