You can apply for a Section 19 Permit instead of a full PSV Operators Licence if you want to run minibuses for reward or hire but not profit from their operation. Your organisation/school must meet certain criteria, such as being not-for-profit or having charitable status.  A Section 19 Permit allows you to charge to cover the costs of running vehicles and allows drivers with standard car licences to drive vehicles under 3500kg provided they meet certain criteria. D1 is the entitlement drivers need on their driving licence to drive a minibus over 3500kg and be paid for doing so under a Section 19 Permit.