Tonight between around midnight and 4am is the peak of the Perseid Meteor Shower. This year it coincides with a new moon meaning the skies will be a bit darker than usual – good for spotting the tiny speeding dots of light produced as the meteor debris burns up in our atmosphere.
There are two things that will ruin your view of the celestial fireworks – clouds and light pollution. Fortunately both of those things are fairly predictable.
Here’s a forecast cloud map for 1am tonight from the excellent website windyty.com. Looking like a nice clear night everywhere but the southern-most parts of England. Good news!
For light pollution, there is a Google Earth map file available from here produced by this guy which shows you where the centres of light pollution are across the whole of Great Britain and more importantly where the areas with low light pollution (and therefore the best views of the night sky) are. Head for the blue areas tonight!