Guidance on Pay and the NMW can be found on Directgov (for workers) and businesslink.gov.uk (for employers):
BERR has published a document setting out how the Government will operate the civil and criminal enforcement of the National Minimum Wage in light of changes introduced by the Employment Act 2008. From 6 April 2009 employers will face penalties if they do not comply with these changes.
Each year the Government submits evidence on the National Minimum Wage to the Low Pay Commission. An archive of past reports is available.
Government evidence to the Low Pay Commission