Is introducing another cat a good idea?

We have a male cat who is petrified of everything, when we got him he was living in a small house with 3 adult cats all with their own litters a child and a big dog, but only 1 litter tray, he is very well litter trained, he was the only black and white kitten there so we took him, he is fine around us and our friends when they have been here a few times, he is petrified of other cats, but when we go away we put him in a cattery 1 time he was there he was put in a pen next to a female cat and he was fine, he was very flirty with her, i think most of the cats around where i live are tom cats and we were thinking of getting him a younger female cat so he has company and someone to play with, anyone else think this would be a good idea?