Update - six months on and the worm bin is working really well; so much so, in fact, that we're not producing quite enough kitchen waste to keep both it and the chickens happy, and I've had to start collecting compostable waste from work as well. Oddly enough, I've become quite fond of the little bleeders too...
http://hedgewizardsdiary.blogspot.com/2 ... ental.html
Best of all, we should be doing all our composting in the bin when winter rolls round, so no more rats. In theory!