You can drive a 9-seater minibus on a standard car licence as that size of vehicle is considered to be a ‘small vehicle’ adapted to carry 8 passengers or fewer, not including the driver. It is not considered to be a minibus.
There are conditions and restrictions on driving these types of vehicles if it is not your private vehicle. If you are driving for an organisation or as part of your employment there are some restrictions on who can drive these vehicles, such as needing to be over 21 and having had your licence for over two years, but you still only need a standard car licence.
An organisation that accepts any sort of payment for providing transport to passengers must hold either a PSV ‘O’ licence or a private hire vehicle (PHV) licence. Section 19 Permits are issued by the DVSA to organisations that operate vehicles without a view to profit to transport their members, or people whom the organisation exists to help, such as school pupils. Section 19 permit vehicles cannot be used to carry members of the general public.
Under a Section 19 Permit drivers of small vehicles adapted to carry 8 or fewer passengers must have held a full licence authorising the driving of vehicles in category B (cars) for at least 2 years and they must be 21 or over. Drivers can be paid for driving a small vehicle under a section 19 permit.
You’re likely to need a private hire vehicle licence if you do hire the vehicle as a whole.
Vehicles adapted to carry 8 or fewer passengers are only considered to be Public Service Vehicles if passengers are being charged separate fares in the course of the business of carrying passengers. This means that if you use a small vehicle you must charge separate fares. The vehicle must not be available for hire as a whole. You’re likely to need a private hire vehicle licence if you do hire the vehicle as a whole. In these cases you should contact your local council, which is responsible for licensing private hire vehicle operations, for advice.