The insurance industry is a rip-off based on using new OE parts at inflated expense. Its why insurance premiums are so stupidly high, even on a cheap, small car and needlessly scrapping perfectly repairable vehicles is typical of our consumerist culture. Don’t repair things, just throw them away and screw some more of the planet in the process.
As above, if you buy the car back and have it repaired at your own cost, it will be Cat C or D and potentially worth less should you want to sell it, but should be perfectly safe to drive. It shouldn’t have an impact on your insurance premium either.
That said, I’d try to make sure that any damage is cosmetic rather than structural if you are going to buy the salvage. Check the rear wheels are still aligned for starters. Bear in mind that because you can use pattern or sound used spares and choose to ignore cosmetic damage, you should be able to repair the car far more cheaply than the insurance estimates.
That’s what we found when someone drove into our T5 and wrote it off last year anyway.