Book value is what it would cost you to replace the car. It's mileage adjusted, and as I said below, you'll be likely to get dealer retail (ie, forecourt price). Trade prices and private sales prices are normally restricted to stuff that's knackered or old.
2x door skins, paint, labour etc, could easily amount to £6 or £700. Though I'd expect the car to be worth enough for that to be no worry.