Toby Manning has written a Guide to Teaching Go (PDF).
Information about Teaching Beginners is also available in Chapter 4 of the Club Organiser's Handbook.
We also have some advice for those intending to run a Teaching event.
In addition we have equipment and other literature that you can borrow/use. See here for the current status.
There's also to a dedicated KGS account that we use for teaching purposes (to Association members only).
Please note that we have an Accreditation System for those who wish to teach in the UK.