"New rules have now taken force which mean that every car now needs to be insured or have a Statutory Off Road Notification (SORN) – even if it's off road and doesn't pay road tax.
If you haven't got car insurance for your off road vehicle or SORN-ed it, you'll need to do so soon, as the DVLA and Motor Insurer's Bureau are expected to begin enforcing the new law from the middle of July 2011."
Ring round a few insurance companies and you will be able to get "special" insurance which applies to SORN cars so will be considerably less than a "normal" insurance policy.
Its not possible to get x months no claims so your no claims for this year will be 0 and you will lose it all. I had to cancel my insurance policy 6 months into it and I got a small token refund but in no way shape or form, despite having only used 50% of my policy, did I get 50% of my money back.