Thanks for you input everyone and yes I agree with the points made across the board -the situation was not a great one to be in and many factors had removed my involvement directly. Imagine if I had decided to leave the car and direct traffic or perhaps make it to the hard shoulder? I could not ensure my safety outside of the car, as the road surface was extremely wet and also people were still whizzing by at a rate of knots - they were simply ignoring what had happened or even stopping apart from the van driver. I could not afford to play chicken with cars, lorries and buses - I would have created an additional hazard by being in the road or escaping to the hard shoulder. As I have been involved with yachts and sailing since the age of 7 years old, I always remembered a rule that 'if your craft is badly damaged but still afloat, then you stay with your vessel unless it is sinking' I suppose that is what stuck in my head. I understood that the police respond very quickly to any incident in the overtaking lanes due to vulnerability of road users.
TDK - yes I agree with you, all I did was call the police - I remained in the car as it was too risky for myself and other motorists if I had decided to decamp and run the risk of crossing to the hard shoulder, there was not anything else I feel I could or should have done. The car was in my opinion the safest place to be. Once the police had arrived, I fitted my towing bracket and steered the car off of the road whilst the patrol car gave me a pull.
I think with this question, it may be difficult for many of us to (a) answer or (b) answer honestly as not all of us have had to deal with or handle an emergency situation unlike a member of the services - in that case you may be ruled out?. Sure, stories can be made up at interview but if your interviewer has any savvy, they can see through this....easier if you can answer from a real life scenario and not make things up - makes for a less stressful interview all round.
I do have some other real life examples I can use - if you don't mind TDK I will ping one across to you.