Copies of the Late Payment Act and subsequent changes (statutory instruments) can be viewed on the HMSO web-site.
Our other web-site - JustClaim contains a simple guide to using the courts to puruse unpaid debts.
Alternatively, visit The Court Service's own web-site. They now run an on-line service for making money claims (look for money claim on-line).
The Court Service also provide a leaflet specifically for small businesses wishing to recover debts; The Courts Service leaflet: A guide to debt recovery through the county courts for small businesses (Leaflet Ex350) .
To find out what interest rates were in force on a given date, visit the Bank of England web-site.