your first post was in Feb. Have you gone any further?
Your car policy is in wife's name. you are buying a van. Is this in lieu of the car, or in addition to the car?
of course you must tell the insurer, you are changing reg numbers - aren't you??
If the van is in wife's name, then the NCB on the car, will transfer to the van, if van is in wife's name. If van is in company name, but you are getting rid of the car, wife's insurers MAY transfer the NCB, but are not obliged to.
If you are buying the van as an additional vehicle, then you have NO NCB on it and you can register and insurer it in any name you want, as long s the registered owner is a legal entity.