Thanks everyone for all the responses and helpful comments. I have found a couple more links to cat houses and will try to post them later this weekend as the page refs are on a different pc to this one, so look again later in the weekend or Monday if you too are looking for cat homes. Will also check out the rabbit hutch option.
Thanks for the link to the recycled houses - particularly liked the site header as it has a nice pig arc on it as well. I really like pigs.
Yes, might be worth getting Tom done, but I would need to be sure for totally certain he is not someone's pet before doing something so irreversible. I guess a rehoming centre would 'do' him anyway.
He does eat in a different area, as he lives in the garden under his bush (which has proved surprisingly rain proof given the weather today) and so I feed him out there. Our 2 cats eat in the (human)house.
I found this link the other day - check it out if you want to see how bright a cat can be, its quite amusing.
http://cats.about.com/od/behaviortraining/a/cattools.htm