I would contact your insurer directly and ask.
If they have declared it a write off and you have accepted a payout, it is legally the property of the insurance company, and I know it is quite usual for an insurance company to ask for the V5 to be sent to them intact, and they will fill out the necessary sections and sign it on your behalf before sending it to DVLA, together with either a certificate of destruction or details of the purchaser of the salvage as appropriate to the category of write off.
You will then possibly need to write a letter to DVLA to inform them that the vehicle has been declared a total loss, and has been transferred to the insurer and that you have sent the documentation (V5c) to the insurance company.
If there was still any reclaimable VED on the vehicle, you will be able to reclaim that by filling in a form V14 and sending it to DVLA with the tax disc attached (assuming you have been able to take the disc out of the car). Only a private owner can reclaim unused VED, so neither your insurance company nor the salvage operator or repairer will be able to do so.