Thanks for the advice, Adam. The figure of £22,000 was based on my estimate of around £16,000 to get hold of a decent equivalent of my car including any fault fixing, another £3000 for courtesy car costs and compensation for loss of car until this is sorted, and £3000 for my injuries, pain and suffering, along with a quick settlement premium.
Of course, if the insurance company don't want to go down that route, then I would accept the other options of a properly repaired car with acceptable courtesy car, or an equivalent replacement vehicle bought and checked to ensure it was fault free.
I would understand that the insurance company will probably want to get away as lightly as possible, but as I am not at fault, I will press the third party insurers to the maximum and am prepared to go to court if necessary. I will of course keep you all updated as to what happens.