Multi-car policy: A car and a van

I have full no claims (x2).  My wife has full no claims.

Today I bought a Caddy Kombi Multi, mainly as a business tool and I want to have it insured for every driver over 25 as it will be used by all those of suitable age in our office.  I've never insured a van before.

Do I:
a. Obtain a 'fleet' insurance any driver quote for the new van?
b. Simply add the van onto one of our existing insurance as a multi car, thus applying the full NCD we currently have?, but this seems to want every driver as a named driver.

To add to an existing policy, I assume the cost will be minimal, maybe £100?, the new quotes I had tonight was £840 for a business quote, with zero NCD and £500 with 9years + NCD as a stand alone personal policy.

anyone?  thanks

Personally I would look to do the multi car option as it would be the cheapest. Most will let another no claims accrue as well. Whoare your current insurers?

I've got mk3 caddy for work, but I have them insured the other way round. 
So my vans on with Brentacher, all mods declared and a commercial van insurance policy cost me £56- a month. And the cars on a classic car insurance, only insured for 5k a year but its only £34- a month.

I have 2 golfs insured, on separate policies but with the same insurer. The Mk1 on agreed value, limited mileage, modified, not using NCB, and a Mk4 with class 1 business using no claims. Have full no claims and me and hubby both 35.
It's with Adrian Flux £400 for both. It cost about £100 to insure the MK4. Worth giving them a try, use your club discount!
Not sure about it being a van as I know it can make a difference on price, but worth a try. I cancelled my insurance on my Mk1 to get a good deal for both cars. Cheers, Anna