Some useful bibliographies etc. are in the Publications section of the ACRL Instruction Section's website. It includes a bibliography on "Library Instruction for Diverse Populations" which I hadn't noticed before. There is a North American focus to the list, but I don't think there HAS been much written in this area in the UK (bit more in Australia, I think?)
Photo by S. Webber: Iceplant after rain, April 2006.