The first step in pension planning is to ascertain how much you will get from the state pension scheme. This link will give you some guidance as to how much you can expect to receive http://www.thepensionservice.gov.uk/...rpforecast.asp
Alternatively you can print off this form http://www.thepensionservice.gov.uk/...ecast-br19.asp
and post it to the department of works and pensions and then they will do a forecast for you.
Then, in order to get some idea as to how much private/company pension provisioning you require, you can use the Financial Services authority pensions calculator for further assistance http://www.pensioncalculator.org.uk/pages/home.php
In many instances, be prepared for a shock
The Financial Services Authority has also issued a list of comparitive tables for the different Pension providers, these can be accessed here http://www.fsa.gov.uk/tables/