Seems we're still getting any bad luck going around!

Friday picked up wife and FiL from hospital. Driving away (dark) a car exited a car park on our right hand side, no lights on their car and smashed into the driver side front and forced us up onto a steep grass bank.

Apologies and admission of fault from third party - he didn't see us. Got his details and he drove off. No witness to actual impact.
Our car is goosed, seems most of the impact was absorbed by my front o/s wheel. Cars steering is trashed and front wheels pointing in different directions. Doubtless unseen suspension, steering and drive train damage

My insurers have indicated car is a write off from my description of damage also accident in their view is non-fault.
I'm also told 'copart' will contact me shortly to remove the car to their premises and advise me of what they consider my car is worth in 5 days time. Not sure that I feel happy with this.

Copart is a national car salvage company, once they have the car I feel I'll have little to none input over what they'll value the car.

WBAC etc buy in values and what dealers (Autotrader etc) are selling similar cars for are miles apart.

Should expect my settlement figure to be similar to what I'd have to spend to get a similar car? Not looking for any betterment, simply to be in the same position as I was before the clown knocked me off the road.

I assume it will be the 3rd parties insurer who'll be covering the cost. I haven't taken the option of a courtesy car ( other cars owned) would not taking the courtesy car - reducing the claim cost, work in my favour for insisting my settlement should put me back in pre-accident position?

Any advice on how get the best outcome would be appreciated. First time in 50 years of driving I'm having to deal with car insurers for a write off.

Thanks :)