I used to work for an assessor’s firm, and so I’ve got a rough idea of how things work.
1) Cash in lieu of repair is better than keeping a write off. Because it doesn’t get recorded as a write off.
2) They will offer you something in the region of 75% of Glass’s guide, probably one of the poorer condition valuations or even a trade in value. They will forget to add options when valuing your car. So if they’ve offered £1600, your car is probably worth £2k
3) Get your own valuations – CAP is free for private people, and has a similar standing to Glass’ with insurers and the trade.
4) Find out what similar cars are actually selling for – ie, ebay and autotrader. Glass’ and CAP can be massively out, particularly on anything with low sales volume or for the fast edition of pedestrian cars.
4) Either be prepared to spend some time arguing with insurance companies, or employ a claims management company. Some of them are awful, some are fine. I used Europa consultants last year, and they were fine, no pushing for an expensive hire car, and pursued the other party for me, which saved a huge amount of legwork on my part. The claims management boys normally take it straight back off the third party insurer, which saves you losing your excess.
As someone who’s had a few cars fixed, anyone quoting you on that job needs to be pulling the door frame into line and probably putting a used door on. You’ll want that gash in the arch welded back up, not just fillered. And an MOT only tests for big holes near vital components and sharp edges – it doesn’t give you any idea of how well repairs were done, so find someone who’s willing to explain how the repair will be done, not just say “£600 guv”.