Thanks, furry - it's been the right thing to do for me, certainly. You will find that you get some very odd tax codes on your other income but they send very helpful notes with them to explain why, K numbers and L codes and the like, it all sorts out so that the total at the bottom of the page is the correct tax and income. I keep a spreadsheet, to keep on top of it all!
Are you still working? Don't forget that if you are, you no longer have to pay National Insurance contributions, which is another saving.
Also, as you get older you get age-related personal allowances against income, mine is £10500 for this financial year before I pay any tax.
http://webarchive.nationalarchives.gov.uk/+/http://www.hmrc.gov.uk/pensioners/reducing-allowances.htm
You do need to keep your wits about you, but it's worth it in the end!