Ok so you want a weekend or even longer away ................
They say the residents of the UK are obsessed with talking about the weather ...........usually with good reason

so where to look for that all important forecast?

try here

http://www.metoffice.gov.uk/public/weather/forecast

add an area, town, or postcode to get a 5 day forecast ..............this is the national weather database all other forecasts are based on