Before you can take court action, you will need to have tried to recover the debt though softer methods.
Business Link has some details about Debt and Debt Recovery.
\link{http://www.businesslink.gov.uk/debt\Business Link: Debt}
Clearly Business also has advice \link{http://www.clearlybusiness.com/legal_admin/ls_debt_recovery.jsp\Clearly Business: Debt Recovery}
Found some helpful information about Chasing Payments at \link{http://www.londonfreelance.org/feesguide/gelattxt.html\London Freelance}
\link{http://www.startups.co.uk/Collecting_payment.Yae4RN1oHWUGSg.html\Startups.com} also offers the following procedure to use when chasing payments:
The sale: Send out invoice
21 days: Send statement reminding payment due after 30 days
30 days: If not paid, send reminder statement, restating terms and pointing out payment is overdue
45 days: Send reminder
50 days: Stop supplies until paid
60 days: Send final reminder
90 days: Assign debt to collection agency
Clearly some of the things here won't apply directly, but the timescale probably does - so keep in touch as best you can with the debter sending out payment reminders, restating terms, until you get settlement, or at 90 days start proceedings to recover debt via court.