C of T?
To rent out an aircraft it must have a C of A which meets the requirements for public transport (hitherto a public transport C of A).
This kind of arrangement works in a self fly hire situation and would obviously then be entirely legal. If on the other hand you are supplying an aircraft AND a pilot the whole arrangement could look just a bit too much like an aircraft charter to the CAA. Any kind of charter arrangement requires an Air Operators Certificate and obviously a commercial pilot.