If a policy has been made void due to a material non-disclosure it basically means the insurance was never in force in the first place.
Should you have had an RTA liability whilst in possession of an insurance certificate, the insurance company would have paid the RTA liability, but they'd've had a right of recovery against you.
When applying for insurance in the future you will need to disclose (1) the truth behind the original lie and (2) the fact that you have had a policy made void because you did not tell the truth originally.
Insurance companies do not like lying (insurance contracts are contracts of utmost good faith) and they do not like people who have previously had a policy voided. It demonstrates to insurance companies that you have little, if any, integrity.
You will struggle to get insurance - not unless you lie of course!