The Office of Government Commerce website (formerly at www.ogc.gov.uk) is now offline as OGC's main activities have now been transferred to the Cabinet Office. However the site contained a number of resources used by many procurement professionals (and linked from this and other websites including the website of the Cabinet Office).
Old OGC content can be viewed as part of the National Archives by adding the following text before the original OGC web address: http://webarchive.nationalarchives.gov.uk/20110601212617/
Click below for example links:
Going forward procurement guidance now falls under the Transparency heading of the Cabinet Office site and the most recent Procurement Policy Notes are available here.