Spidermama,
Sorry, haven't read much of the rest of the thread, but we got our cats from the Cat Protection League, and they advised us the same about keeping them in at night. However, I feel like you that cats should be out at night, as they're nocturnal animals by nature! We have a cat flap for ours, they come and go whenever they want, and we don't have to keep a lit tray indoors (which would be a nightmare with small children...).
Ours were really nervous at first, but once they were confident in the house and with us, we started letting them out. With us at first, but soon on their own. We lived in Ealing then, and it wasn't quiet roads, countryside etc.
The Cat Protection League won't give you a cat that isn't spayed. It's unspayed cats, ime, that cause problems re. fighting, roaming large distances, esp. tom cats, who also breed, leading to more strays.
Saw the question about de-clawing cats. I think that's really really disgusting and cruel. A cat without claws can't jump up a fence, or balance on one either.