I had a crack at the pid kettle, it took one trip to the hardware store and about two hours of my time - it was easier than it sounded! Photos: www.flickr.com/jasonscheltus
Instead of ripping up the kettle I just used the mains plug and made sure the kettle stayed on. It works okay, I just have to play with the pid values.
I added a photo from the top to show the wiring basically. Brown=active Green/Yellow=Earth/Misc! Blue=Neutral.