Category A is the worst damage and probably not repairable. Category D is slight damage.

With flood damage, it is possible that some electrics might work now but, in a few months, corrosion might cause problems. Corrosion on electrical connections isn't a serious problem (a rub with sand paper and a squirt of oil usually fixes things) but finding which connection is at fault can sometimes be time consuming. It is also possible that some bearings or similar parts that are normally packed with grease could require replacing sooner than would normally be expected. Such things should be reflected in the price.

If you wanted to get an MOT you could but this isn't necessary until the car is 3 years old. Similarly, any inspection is for you to decide about.

Some insurance companies wont insure a category A write off but you shouldn't have any problems with a category D car.

I'm interested in buying a car that has been given a CAT D rating due to low level flood damage. To all intents and purposes the car looks in immaculate condition. I've been told that it drives well and all the electrics seem fine. The car is less than 18 months old and therefore has no MOT certificate. What coarse of action should I take so as to have the car insured? Would proof of an engineers inspection report be enough or would I need to have the car mot'd?