Insurance Contracts are contracts of "Utmost Good Faith" which bluntly means you each come to the table with your cards openly shown. If you deliberately misinform your insurance company about "Material Facts" under a policy then they have the right to refuse payment of the claim or void the policy from inception ( void ab initio).
Usually in these circumstances insurers will have to foot the bill for any third party claim because the Road Traffic Act dictates they have to , but they will try and reclaim any outlay off you.
Is it Insurance fraud? Probably not but one which lawyers would argue over.
My advice would be to shop around, maybe go TP only?
Could you lay the car up part of the year and just insure it for Road Risks for say 3 months of the year?
I'm really sorry your in a bit of a jam with the insurance and maybe cant afford it.
Hope you can resolve it . Joker182