As an employer you need to make sure that all your employees are trained well enough to be able to work safely.
If you use Supervisors or Managers to deliver in-house training, they should be experienced and competent in the type of work or operation on which the training is to be given.
They may need additional training in the specific hazards of the processes and how you expect the risks to be controlled.
As an employer or a self employed person, you will need to keep yourself up to date on how to identify any hazards, and control the risks arising from your work.
You will also need to know about consulting employees or their representatives on Health and Safety issues. There may be areas where extra training would be beneficial.