Do I have to wear a seat belt on a forklift?
Yes. under the L117 ACOP: if a seat belt is fitted it must be worn.
Yes. According to the HSE's L117 Approved Code of Practice (ACOP): if a forklift truck is fitted with a seat belt it must be worn. Seat belts help prevent operators being thrown from the vehicle or crushed in the event of a tip-over.
Useful links
L117 ACOP