Here is a link to the page http://www.bookkeepers.org.uk/Membership it tells you what you can and can't do at each level.
If you are a member of the ICB you need to be qualified and have a practice licence to do the final accounts. Once you have a practice licence and passed level 2 exams you can do final accounts for sole traders only, then once you have passed level 3 exams then you can draft for limited companies and partnerships.
Here is the link to the info about the practice licence, http://www.bookkeepers.org.uk/Resources/Running-a-Practice the licence and insurance will only cover you for what you are qualified to do.
Edited at 21 Jan 2014 03:34 PM GMT
Edited at 21 Jan 2014 03:37 PM GMT