It'd be interesting to find out how much the Ampera sold for as spares. I'd expect around £4k. The seller would take a %, then the balance to the insurer. So the payout by your insurer (I'm estimating £10k) would be somewhat mitigated.
I think you'll reflect you made the right decision. As an aside, the Vauxhall demonstrator on Autotrader with a £14k asking price is still unsold. Did you view that one?
I think I have made the right decision given the circumstances. The 'Old Growler' (pictured above) that I replaced it with is more or less the same size and colour and, being a modern automatic, is very similar to drive. I have yet to measure the running costs but being a modern 'eco' diesel, and given the increases in electricity costs, it will not be significantly more.
Nevertheless, I do miss the Amp. - it was a great car. I believe it sold for a little over £5k with the auction fees and delivery etc. to be added on top of that. I have met the buyer who kindly cleared the hard drive for me and delivered the CD that I had left in the car - I was pleased to present him with the owners manual and second key in return! He has two other Amps. and a Tesla. It is good to know that my old Amp. will be carefully restored.