What's the value of a cat s and cat n car?Watch this thread
How it depreciates is a harder question to answer. If the repairs are done to a high standard it shouldn't make a huge amount of difference on the resale, the depreciation should be the same as a normal car.
Reselling your car can prove difficult too as many won't want to buy a cat n,s car - Cheap to buy and cheap to sell
Some good cheap bargains can be had, sometimes about 30 to 50% lower price than non damaged used cars
However - some insurance companies won't insure either category. Some insurance companies require a structural engineer to inspect your car, others just ask for another MOT test.
Oh deep joy