It is 50/50, so your Insurers are already paying 50% of the third parties claim anyway, so it does not make any difference whether you get your car fixed or not. If you can afford to pay the excess, you might as well get the car repaired and should arrange this with the Insurers.
You will lose some of your no claims anyway, unless it is protected. You lose 2 years for each claim normally, so you should expect a fairly steep increase in premium if you still need the Insurance at time of renewal.
If you do sell the car before the renewal and look to cancel before renewal, you will still have to pay the full years premium and you may also have to pay a cancellation fee.