Dave - I run an online workshop (ie. participate from anywhere in the world, provided you have a PC and a broadband connection) once a month on the topic of succeeding in case study interviews. We cover the various types of questions you may be asked and work through examples of how to tackle each.
If of interest the next one is this Friday and you can <a href=http://www.top-consultant.com/UK/events/Article_display.asp?ID=140>sign up via this link</a>
Good luck in any case - and hope to see you on the call.