So you may unfortunately now have a quite unique insurance problem, I always put my cars in storage on a specific storage policy as RTA (Road Traffic Act) insurance may have conditions applied eg with regards to access to keys, which if left with the storage company to maintain it or with the vehicle may invalidate the RTA insurance. I've learnt that from experience having had my car plus 15 other owners cars stolen whilst in storage, every other car was on RTA insurance and mine was on a specific storage policy and only I got paid out because of the key clause. So I would be looking for an Insurer that can switch your policy between a 6 month RTA and 6 month storage policy, a broker that deals with car storage maybe able to point you in the right direction.