If the accident was not your fault,  the other driver’s insurance should be responsible for fixing your car and providing you with a replacement vehicle while your own is being repaired.  You will need to obtain a repair estimate from your local garage/dealer.   If your car is unfixable or repairs would exceed the value of the car (uneconomical repair) the insurer should pay the market value.   Many factors are taken into consideration when looking at the market value of a vehicle i.e. valid NCT, mileage, overall condition.