There is a six-year statute of limitations for property damage. However, I would not advise you to approach the council again in case it invites a claim against you.
As for the cancellation fee for the written-off car, it is normal practice that you will have to pay the full outstanding premium if you have a fault claim.
And when it comes to your van insurance, unfortunately, the claim hanging over you is relevant. Insurance uses a system of risk-based pricing as property damage was caused. Although the claims process is taking some time, the damage is still a material fact relevant when an underwriter considers your premium.
So, unfortunately, all I can advise you to do at this point is to sit tight and any time you look for a new insurance policy, make sure to shop around for the cheapest premiums you can find.