Selling a CAT N

[fiatpower]

My wife had an accident a couple of weeks ago where she was spun and pushed sideways by a lorry on the motorway at around 30mph for a short distance. The car went off for an assessment but has subsequently been written off due to a number of panels needing changing and some paint work required. A lot of the damage they have noted down is very minor and could be repaired at a far lower cost than replacing for new like they do.

It needs a new door and front wing with a few dents pulled out of the rear quarter. I can change the panels and a friend could spray them as he does body repairs on the side. The tracking was off when I drove it so presume there's some damage to the suspension which are probably track rod ends but again this is something I could do and have done before.

She wants nothing to do with the car understandably but I want to buy it back off the insurer. They gave a price of £700 with the vehicle having a market value of £6k. Even if the recat drops the value by half I think I could make a fair bit of money off it. My only worry is the process of reinstating the body to the road and selling it as a Cat N. Is there a set process to follow? I couldn't see anything on google but it seems a bit strange that theoretically I could just repair it and stick it back on the road. I was personally thinking of doing the work and then getting an AA or RAC assessment done on it to cover myself. I would have got it MOT'ed but that was last done 2 months ago. Is there anything else I could do?

[fiatpower]

I'm not concerned about the repair. I am mechanically competent and always do my own work. My friend works in a body repair and paint shop and would do the work on the side for me. I'm concerned about the legalities of selling it on as it seems a very lax process. I would have thought it would need inspecting officially before being deemed roadworthy again but it doesn't seem that way. I was just wondering if anyone has done this before and has any suggestions.