The age old question.......
I dont see why you cant integrate another cat into the household if you give some thought as to what character of cat would work well with Chuckles personality, now you've got to know her better.
I think the people where you got Chuckles from may be able to help you with this, as they should hopefully have some insight into Chuckles character, how she was when she was among the presence of other cats in the rescue, and help to guide your instincts in that direction. It's not foolproof, because cats are seldom at their best in a rescue situation, but it may give you useful pointers to bear in mind.
When we had Paddy, he was 4 when we introduced another cat, in the form of an 8 week old kitten from a litter my stepdaughter's cat had. Paddy was devastated. He began to stay out more and more and wouldnt come in unless he could avoid Flynn.
That was a huge shame, as Flynn adored Paddy and just wanted to hang round and spend time with him. Over time Paddy grew to tolerate Flynn, and they would share a bed together and were companionable enough, but when Flynn disappeared whilst we were devastated, Paddy was undoubtedly happier.
Paddy felt obliged to "compete" when Flynn appeared. Flynn was a great mouser. Paddy wasn't bad, but where Paddy would catch one, Flynn would catch two - not in a supreme display of "one upmanship" - far from it. It was one for each of them - it was just Flynn's way - he was a happy and loving cat and he wanted to share that love with his big brother.
Paddy didn't see it like that. He saw it as "added pressure" - a slur on his abilities. He grew anxious and introverted. He looked (and I guess felt) hunted.
When Flynn was lost, Paddy reverted to his previous position of "relaxed cat" and so we never replaced Flynn. Paddy remained an only cat until he died because that was what worked best for him.
However, many people integrate other cats very successfully, and Ross (our gorgeous golden boy) has befriended our neighbours young cat (about a month and a half younger than Ross) who spends a large amount of his time dossing at our house, so I guess Ross is a more sociable cat, although I also think Dickie's character works with Ross's own, so they rub along well together. The again, Ross was used to a multi-cat and multi-dog household, so it probably seems a bit lonely to him to have only us humans for company. He would've loved our dog.
Personl experience suggests to me the various character traits are really important when trying to choose cats that have a greater likelihood of rubbing along well together, and it's a philosophy that I found endorsed in an American site called The Way of Cats. I particularly liked the following, which I think was really well observed:
http://www.wayofcats.com/blog/cat-typesHaving said all of that, as Liz and Rosella, JS, Angie and many others here can testify, when a cat happens to turn up out of the blue, sent by the Great Celestial Cat Agency, in need, or sick or whatever, they've often been just as easily absorbed into an existing cat family without too much difficulty.
I'd see what happens when you "go for a look."
One more thing I would say is that it might be worth while considering if you're going to get a flap put in and allow Chuckles access outside, getting another cat may be best done before you start letting Chuckles out, so they have time to get to know each other to minimise the risk of Chuckles staying out in a sulk. Also it could be tricky trying to allow one cat access and not the other (unless you get a microchip flap of course, as then you could have Chuckle's chip entered into the flap's memory, but not your second cat until you were ready for them both to go out together).
I suspect your surname now will be "Smitt."
