You do not need a driving license to drive a forklift truck unless you are required to operate it on a public road. This is unlikely but can happen.
The miminum age to take a test is 16 years old, there are 6 registered bodies that run accredited courses:
• the Association of Industrial Truck Trainers (AITT)
• Lantra Awards
• National Plant Operators Registration Scheme (NPORS) Ltd
• the Road Transport Industry Training Board (RTITB) Ltd
• the Independent Training Standards Scheme and Register (ITSSAR).