1. There is no such thing as an 'AFI' any more.
2. Only the military has 'QFI's .
3. Have a search on
www.srg.caa.co.uk for the renewal requirements - your last revalidation should have an expiry date and that will dictate your renewal requirements.
4. If you have a 'No applied instrument' restriction on your Rating, expect to have to do a course and test to remove it.
5. You'll probably be expected to have a good working knowledge of the relevant JARs covering your licence, ratings and those for which you'll be instructing. I'd recommend that you buy a copy of LASORS - it's only £10 - and it'll answer all your questions!