This isn't very well laid out, but it is up to date and accurate:
http://www.dti.gov.uk/employment/employment-le gislation/employment-guidance/page15686.html
For redundancies made before 1 October 2006, the amount will be calculated as -
* For each complete year of continuous service between the ages of 18 and 21, you will receive half a week's pay.
* For each complete year of continuous service between the ages of 22 and 40, you will receive one week's pay.
* For each complete year of continuous service between the ages of 41 and 65 you will receive 1� weeks' pay. However, if you are over 64, the total amount of the payment you receive will be reduced.
For redundancies made on or after 1 October 2006, the amount will be calculated as �
* Up to the age of 21, you will receive half a week�s pay for each completed year of service.
* 22 � 40 years of age, you will receive one week�s pay for each completed year of service.
* 41+ years of age, you will receive 1� weeks' pay for each completed year of service.