Update.
Insurers have decided they want to write the car off as a CatS because of the bent A pillar, the write off is no surprise given the costs in a body shop as highlighted above, but I was hoping for just uneconomic repair. I have an option to keep the car but I'm away for work in 2 weeks for 6-12 months (the A2 was supposed to be coming with me) so I have put the car into the Market place. If no one is interested I'll try and store it at home and get onto it next year. I've had the argument over the category but their engineer isnt budging.