Hi there,
Just thought I would drop in with a bit of advice.
The first thing i'm going to say is be very very careful with that rotary polisher. For beginners we normally recommend starting with a Dual Action polisher, you have to work very hard to damage paint with a DA, whereas you can quite easily take off a hell of a lot of paint if let loose with a rotary like the one you have linked too without a bit of experience.
Onto the claying, there are a few mild clay's out there, something along the lines of Meguiar's Smooth Surface Clay Kit is a good one to start with, or maybe Dodo Juice Born Slippy with Dodo Juice Gentle Grey, both can be found here:
http://www.waxamomo.co.uk/productcart/pc/viewCategories.asp?idCategory=4Have a look at the video on the Smooth Surface Clay Kit page, it is a Meguiar's video but will show you how to use it properly.
There is already some very good advice in this thread for you.
Chris
