As far as shots, you might want to check up on the laws in your area. Here in the US it's required that ferrets have their rabies shots, but if you don't need it there in the UK then don't get it cause it does more harm then good and ferrets do not get rabies anyways. Also, although not required, it's a good idea to get a canine distemper shot if you have problems with it over there.
As far as food, it also depends on availabilty, if you cannot find a good ferret food, then you can try giving him a high quality kitten food(at least 35% protien and as little fiber as possible). Also, try to get a food with little or no fish because fish makes the poo smell REALLY bad.
You need to try and let the ferret out of the cage for about 4 hourse a day. I fecommend breaking it up into 2 2-hour sessions. Otherwise he may get destructive and start digging in his food/litter and making a huge mess of things.
As far as bedding, nothing explains it better then a pic, so here's a pic of the top half of my cage(the little guy in the photo is my foster I just got 2 days ago):
And here are a couple other cage/bedding pics of mine, to show you all the different bedding options(I make my own bedding, so my ferrets are pretty spoiled, lol):
Since you're going to just have 1 ferret, then I would recommend having at least 1 hammock and a cube(or something cave-like he can hide in). In nature, ferrets(the black-footed ones) live in tunnels, so they like to hide.
Oh yeah, about cats and ferrets. Let the ferret out around the cats and watch them at first and make sure that none of the cats is going to try and attack him(or visa versa, lol). As long as they get along or ignore each other, they should be fine. I own 3 cats and 4 ferrets(I'm fostering one right now) and all my animals get along wonderfully.