Thanks Exup.
Regardin the roof, running my finger from left to right I can feel dips in the roof of the car where above where the hinges are fitted. The hinges themselves are not bolted directly to the roof so not sure how, but something has pulled the roof down in these points.
For the tailgate, it will need replacing. The outer skin and the frame are both creased.
The reason I think the chassis may be twisted is the car hit us at an angle, he was trying to get to the left of us as we avoided a car by swerving to the right. His o/s bumper hit my n/s bumper. In addition, the 3rd row seats now have a larger gap between them and the side of the car to the left than to the right and the car now pulls slightly (only slightly) to the left. With the steering wheel slightly off centre I can go in a straight line but this was not like that before the impact.