Ghiabox:
Just realised i put minubus not minibus, nevermind. So as long as it doesn’t exceed 3.5 ton which it will likely be very close to considering the van will weigh approx 2.5t without passengers.
A cat D1 would enable you to drive a 14 seat minibus, a Cat C has no relevance to the PCV, As you passed your test after 1997, you do not automatically get Cat D1, last I recall was required therefore you are driving a vehicle not in-accordance to your licence. Thus, your not licenced, or insured on said vehicle. Cat B allows you to drive up to 9 seats.
Basically,if the rear of your licence has no D1 printed on the back your not legally permitted to drive the vehicle.