If I understand you need that: http://www.jibble.org/ukpostcodes/
If not - here is a lot to find:
http://zipcodecoords.codeplex.com/
http://zips.sourceforge.net/
http://www.vclcomponents.com/s/0__/coordinates_zip_code
http://pyqgis.org/repo/contributed/
http://www.nearby.org.uk/coordinates.html