I had a similar accident last year and got an accident management company to sort it rather than use my insurance – they were very good and saved me a lot of hassle.
The third partie’s insurance co. made an offer minus 10% and told me to keep my car as salvage. I wasn’t given any other option and according to the acc. management co. this is what usually happens now as it saves the insurance companies time and money in not having to deal with written off cars.
I had my car repaired and put back on the road. Once its been declared a write off you have to take it to a vosa station to be inspected – not for the quality of repairs just to make sure all the chassis numbers are correct and you’re not trying to register a “rung” car. You’ll then be sent a new V5 which will state that the car has been involved in an accident.
I think some insurance cos. expect you get an mot at this point but I’m not sure. Probably worth doing anyway for peace of mind.
The only way it affected my insurance is that the car is worth a lot less in the case of a payout but its a good idea to inform the insurance co. that the car is now a cat c/d.