UK postcode Distance

I am looking for a uk postcode file with towns, cities etc. I also need the distances marked from lands end or some reference point. This is needed to work out the distances. I want to use the database to carry out search results within a given distance from a town. e.g. Eastham is a Town in London and I want to search within 3 miles distance from Eastham or E6 (E6 is the postcode for Eastham). It would also be nice to be able to search via “North/East/South/West London” I want to be able to search by any distance from either town name or postcode. To see an example of this, go to [login to view URL] and select “Search Area” on the top left-hand side.