Although you have separate car insurance policies, your mutual assets would still be at risk because you are married. Your husband's car insurance would be the one to pay for the damages but if the damages exceed his policy limits for liability
then your husband would be responsible for the remaining damages.
Furthermore, you need to consider if your husband's policy allows for a "permissive use" condition. A permissive user is an individual who does not live in the listed residence and uses the vehicle irregularly. Meaning, anyone who drives the vehicle regularly (more than once a month) or who lives in the household needs to be listed on the policy.
The last thing I would think about is if the fact the driver is unlicensed would impact your husband's ability to file a claim. While it can vary by the conditions within your car insurance policy, an insurance company may deny your claim because your husband willfully allowed for an unlicensed driver to use his vehicle.
Your best bet is to speak with your husband's car insurance prior to letting the unlicensed driver use the vehicle. Best of luck.