How old is this gun ?

I concur with Fly and Pete above.

The general condition is right on the cusp; get it refinished tout suite and you'll have a really nice lightweight game gun. Do nothing and you've got a worthless chunk of rusty steel only fit to prop the greenhouse door open. The woodwork although shabby would come up very nicely, it's not too bad at all. The barrels are where the real work needs to be done; a skilled filer would get them back to rights no bother, but rubbing away with abrasive paper won't.

From the style I think it pre-dates WWII by quite a bit. To give a better answer as to date we'd need to see some clear pictures, close up, of both the barrel flats (ie between the action hook and the ejectors) and the action flat (sometimes called the water table). It almost certainly has 2 1/2" chambers and should not be fired until inspected by a competent gunsmith with the experience and tools to make a fair assessment.

It's a typical mid quality Anson and Deeley non ejector, with a Hackett snap on fore end, Prince of Wales semi pistol grip, nice acanthus leaf engraving, drop points, and vacant (or at least I think it is) nickel / silver escutcheon. It was made by skilled men who knew their business, from first class materials. All in all a nice gun in it's day.

If you're handy and not afraid of doing odd things, you could...

Get a very large stainless steel pot, the sort you get at a thrift store for a few dollars and fill it with rain water or distilled water. Set it to boil.

Take the forearm off your barrels, of course, and boil the back end of those barrels for 30 minutes. Turn the barrels over and boil the muzzle for 30 minutes, then lay the middle across the steaming pot for half an hour. Remove your barrel which will be the temperature of boiling water or so.

While waiting for it to boil, gently gently gently address the big rust spots with a COPPER scrub pad. Many are copper coated steel which is NOT ALLOWED! You can get one for certain online called "Big 45 Frontier Metal Cleaning Pad" and go very gently.

You'll have a scary looking orange powder on your barrels. Do not panic, you're doing God's work. This can be easily brushed away with a copper or bronze cleaning brush.
Never use copper coated steel!
You are converting horrible red rust (Fe2O3) to black iron oxide (Fe3O4) which is stable and an old technique for bluing guns that is very good.

As the barrel is hot, it will dry quickly. Don't touch with your bare hands because it's hot and to keep hand oil off it.

Next, coat it in an oil or turpentine which does not have an anti-rust additive in it. You do not want to stop this conversion process. Wrap your turpentine soaked barrel in plastic for a few days.. this will let the conversion process complete as far as it's going to go and remove water.

Then you can clean it all up, run brass brush and patches down your bore with the usual gun solvents.. and coat the whole thing in good gun oil (I like Clenzoil because it smells good and is at the hardware store, and is in a pump bottle... not aerosol can.)

This might seem like a lot of risky work, but it will stop your rusty blobs. Don't sand or polish your barrel and I would not put cold blue (little more than paint) on it either.

Your barrels will be shiny and BLACK. You will have pitting, but don't mess with it- us amateurs can do more harm than good with sandpaper, wire wheels (eeps!), stuff like that.

Let me stress what you have-
That engraving? That was done by a skilled craftsman! Be careful with it and gently in cleaning with a toothbrush and non-abrasive. Clenzoil is good.
That checkering in the wood? Another skilled craftsman! Don't hurt it! Toothbrush and all natural furniture polish... no silicone!
That wood? You just can't get that sort of old growth hardwood without paying thousands of dollars for it. (really)

If you just put it in a closet, the rust will slowly eat away a special bit of history, craftsmanship, and something a gentleman can still take hunting with just a little bit of care (and not factory ammo off the shelf but certainly nothing so rare it can't be ordered on the web.)