Not clear on this. Why are they saying you need to be the main driver if you are not ? Or are they saying that you need to be the policyholder as you are the registered owner/keeper shown on the V5 reg doc.
I personally use the comparison sites to guide me as to what the current market prices are, but I still research elsewhere. It is important that you read all of the information carefully and enter the information that is requested. Otherwise the quotes will not be accurate and the Insurers will adjust the premiums if you phone them.