I live in Manchester, and teach knapping, both modern, and paleo. Wee problem though. Being Manchester, Washington State, U S of A is likely no help, eh! That said, your local University should have somebody adapt at knapping. Failing that, have a look at the group I am active with web site (Puget Sound Knappers), we have many tutorials you can learn from. There are also many links to other sites. It is easier for most to have hands on teaching, but careful watching of the videos, as well as reading about the basics should get you going. If this is a small group of friends, the video, and reading should work.
Woody