I had quite a problem getting insurance for my vehicle, most didnt want to know as soon as I said "Van". I tried getting quotes from "commercial" vehicle insurers, but these were in excess of £1,300.
In the end I used Direct Line they will insure any vehicle, and the policy specifically says you can use it for business use.
Be warned though, you cannot use your no-claims bonus on more than one vehicle at the same time. This is a common mistake, but you'll find if you have an accident you wont be insured.
So I put the car in my wife's name and use my NCB on the van.
The premium was about £600 without the NCB or £300ish with it applied. (This was fr an Escort 55)
-Philip