Gracesgran, The government already has information about how much tax we pay and benefits we receive. When I 'supported' my daughter's application for student finance a couple of years ago, I was told that I didn't need to provide any further information, because they already had all the information they needed about my income.
It's actually worth checking it, if you still have the relevant paperwork, because the various government departments do make mistakes. In most cases, I don't suppose it really matters if they're a few pounds wrong, but it does matter for pension eligibility (I have three estimates and still don't have a matching pair) and would be even more important, if the information were to be made public.