Strictly speaking, there's no such thing as a 'forklift licence'. However the law states that "Every employer shall ensure that all persons who use work equipment have received adequate training for purposes of Health & Safety, including training in the methods which may be adopted when using the work equipment, any risks which such use may entail precautions to be taken". [Provision and Use of Work Equipment Regulations 1998].
For general advice on employment issues, call the Acas Helpline:
https://www.acas.org.uk/contact
To report specific issues, use F-F's link.