A complex subject, and one on which you should certainly take professional advice as mistakes can be irrevocable and expensive. The sites listed below will give you a good basic background to your enquiries.
See also the topic pages on SIPPs and on ISAs.
the Government website giving advice on pensions
http://yourmoney.moneyadviceservice.org.uk/hubs/home_pensions.html. Set up by the FSA, the Money Advice Service gives free unbiased advice on pensions and retirement.
http://www.pensionsadvisoryservice.org.uk/ an independent not for profit site giving pension advice
Keep in touch with the latest changes in pensions regulations: http://www.teefinancial.com/lib/pdf/ChangingFaceofPensions.pdf
You can also call the DSS information line: ‘Pensions Info-Line’ on 0845 731 3233 to find answers to your questions