If you've been made redundant, your employer will normally pay you either on the last day of your notice period or shortly afterwards, or on your next pay day.
If you haven't been paid, or if you've been paid but are unhappy with the amount, you should try to sort the problem out directly with your employer first. Write to your employer explaining the problem and asking for full payment. Your employer should give you a written statement showing how any payment has been calculated.
If this doesn't work, you can apply to an Employment Tribunal. You need to make a claim within six months, otherwise you might lose the right to a payment.
From here:
http://www.direct.gov.uk/en/Employment/Employe es/RedundancyAndLeavingYourJob/DG_10029836