UK Pressure Map
Below is a live UK Centered European Surface Pressure Chart courtesy of the guys at Meteorologica.
The circular lines on the chart are called isobars. Isobars are lines joining areas of the same barometric pressure.
Air flows clockwise around areas of high pressure, and anti clockwise around low pressure. The closer the isobars are together, the stronger the winds.
Because the Earth's rotation, weather systems tend to move from the west to the east in the UK. The jet stream also strongly impacts on the direction of a weather system, so you'll often see low pressure weather systems moving rapidly North-East wards.
Other weather related pages include UK Weather and UK Lightning Map