I'm a Senior Observer in the IAM and also taught on our skidpan. Red Robin is correct in that with the IAM you
may get someone who is very rigid, but when you sign up for a course and you contact your local group, you can suggest that you are an 'enthusiastic' driver and you would like your observer to be someone more, um, progressive

I can assure you the IAM is full of us little rebels and my policy is maybe more progressive than most, but then I've never had an associate who's failed yet!
The track day and the IAM really go hand in hand, but are quite different things in that the track day shows how to control your car when things go a little wrong, whereas the IAM uses roadcraft to prevent things from going wrong in the first place. Any fool can drive quick and go off at the first corner, that requires only luck as guidance and it's only a matter of time before that runs out, the real skill is to be able to drive quickly and smoothly within the conditions and your vehicles capabilities.
As a free plug if anyone in Shropshire fancies the IAM course have a look at our website and I may see you shortly
www.advancedmotorists.org 