“Planning permission is now required to lay traditional impermeable driveways that allow uncontrolled runoff of rainwater from front gardens onto roads, because this can contribute to flooding and pollution of watercourses.”  

Source: Guidance on permeable surfacing of a front garden. Communities and Local Government and Environment Agency.

Basically, from the 1st October 2008, planning permission could be required  if you wish to lay an impermeable driveway without sufficient provision for the run-off of rainwater.

First of all, this is nothing to be too alarmed about. The planning regulations have been introduced to help manage the amount of water entering the surface water drains and only applies to front gardens. There are however, possible alternative solutions which don't involve the need to apply for planning.

If the area of hard surface is constructed using a permeable product such as Marshalls Priora range or Marshalls Grassguard, then the water is able to escape into the ground and does not contribute to increased run-off rates. There is no limit to size in this case.

Standard impermeable paving can be used if sufficient provision is made for rainwater to drain into a soft landscape such as grass or border planting with sufficient permeability, or into a specially constructed soakaway. If the area of hard surface intended is less than 5 square metres, then no planning is needed, regardless of the surface material.  

Elsewhere around the house there are no restrictions on hard surfaces at or near ground level. If in doubt, you should speak to your local Planning Officer.