Types of Cover
Third-party covers damage you cause to others (minimum for many). Third-party fire and theft adds those. Comprehensive covers your vehicle too (accident, theft, weather). Premiums depend on value, use, driver history, and where the van is stored.
What to Declare
Be accurate about value, modifications, and use (private, business, rental). Non-disclosure can void cover. Some insurers specialise in motorhomes/campervans; shop around.