There's three ways of dealing with it...
1. Make no claim, and swallow the cost. Upside no 'stigma', downside out £1200.
2. Claim through third party insurer, get several quotes and car gets fixed to everyones agreement. Depends on third party admitting full liability... they may even agree a cash settlement

car not written off.
3. Claim through own insurance on the basis that third party is liable. Car gets written off, probably Cat C as that's the mentality at the moment. They buy the 'wreck' from him by way of paying the suggested £3k. He then buys the car back for it's salvage value. If the car is still driveable and in his possession then it is a virtual exercise. He keeps the car, receives £2750 ish and gets the car repaired. Yes it will be a Cat C, and will need a fresh MoT and VIC before it can be used on the road again (if the car is still insured with the same insurer

) they might knock cover down to 3rd party only until they receive the VIC certificate.
To put a couple of myths to bed...
1. The salvage value is the price that Copart buy the car from the insurer for, typically scrap value unless the car is rare or specialist.
2. Once written off, always written off, the VIC check is purely to ensure the legitimate identity of the car. The fresh MoT that is required is a demonstration of roadworthiness... ie a poor repair might fail the MoT.
3. If the car is still in possession and still driveable then you have more options in reality than if the car is in an insurance pound. If the insurers have it, best bet is to get all your property from the car, take the money and run. They could turn round and say 'Here's your £3000, less £250 salvage value, less your £300 excess, less 10 days storage (at £50 per day) £500, so an actual payout of £1850. Still with a £3000 claim on the policy. If not at fault his excess will be repaid.
If there is any question of liability, ie less the 100% third party admission, and he still has the car, then my advice, from experience, would me to notify the insurers, and make no claim. Worth checking with the insurers as they may already have written the car off prior to making there offer. This was how my Omega was written off the first time. Technically it shouldn't be written off until the claim is agreed and settled, but insurance companies are nothing more than self serving onanists, and do things their own way. Even if the claim is not made, once the car is already written off, that cannot be reversed
