The .30-30 will be found all over the Internet because about 7,000,000 of them have been sold since 1894, and Winchester and Marlin still make them and sell them steadily today, all over the USA.
As already stated, it fires a 170-gr flat nosed bullet at 2,200 fps or a 150-gr at 2,400 fps. The 20-inch carbines were designed to fit in a saddle scabbard, stage coach or overhead compartment on a steam locomotive, and are handy for hunting in the woods. The trajectory is a bit of an arch, making them best for 100-yard hunting. Inside 100 yards they are very effective on deer, and even boar, bear, elk and moose.
In the hands of a marksman with the right sights on a 24-inch barrel rifle of some accuracy, the .30-30 can easily take a deer cleanly at 200 yards, especially with handloads of 150-gr, 130 or 125-gr spitzer bullets, used as a single shot. But few people do that. I am one of them, using a Marlin half-magazine 24-inch barrel Model 336 Deluxe, and I enjoy it.
The Winchester, having top ejection, is not amenable to a scope, unless you get the more modern 94AE ( Angle Eject ). The .30-30 is too much power for a fox.
So my suggestion is to listen to your fellow UK deer hunters, get a mild-recoil rifle like the .243 which is very common there, very accurate and very versatile for anything from fox to large deer; and there are tons of nice used ones to be bought.
Then, if you still have the itch for a lever action, get one in a handgun caliber, like the .357 Magnum /.38 Special, for lots of cheap and fun shooting. I hope you do, and get the bug later for a .30-30, .444 Marlin, or .45-70, or a Savage 99 or Browning BLR firing a bolt-action cartridge.