i dont know how old your coop is but if it is 10 years + then you can get classic insurance which is much cheaper.

Its an N so 10years yeah what companies do classic insurance?

adrian flux do classic insurance on cars as young as 5 years! also, if you limit your mileage and are a member of an owners club you get discounts.
but remember that they will only give you market value if you make a claim even if you've spent thousands on modifications.
hope you get a good quote!
p.s. if you key in classic car insurance in google it will give you even more companies to choose from.

I don't no if this will help. When I lived in the UK as a young guy, some mates and I all had performance cars and had the same trouble that you are haveing now. We went to an Insurance Broker and he set up what was called a "Block Insurance" for six of us. This allowed us all to drive one anothers cars, and also worked out much cheaper for each of us. For me it meant only haveing to pay 80 pounds as my part of the deal, where if I had taken out the normal Policy, it would have cost me 280 pounds.
Good luck with this, Barry.