On the whole, with the majority of commercial vehicle policies, whether for car or van, it is possible to add a spouse on to the policy for social, domestic and pleasure use.
As always, policies can and do vary from one insurer to another, so this option is not automatically available, but it is very rare for it not to be. If you are unlucky enough to have been placed with an insurer that does not offer this, then it is a simple matter to cancel and transfer the policy to another insurer that does.
Provided you haven’t made a claim when you change from one policy to another, you should receive a credit for the unused portion of the old policy. This will be used against the premium of your new policy, which will run for the usual 12 months as long as there are no further changes made.