As part of your normal policy it's unlikely you'll find any. You can pay extra for a guaranteed hire car, even then it will only be a class A. All the big insurers will provide this, but that does not answer your question. You could try contacting a company, like Autonet (www.autonetinsurance.co.uk/van-insurance/guarantee...e) or Plan Insurance (www.planinsurance.co.uk/taxi-insurance/guaranteed-...e that could provide separate policies) for a Guaranteed Hire car. They may be able to provide the size of vehicle you require as part of the policy.