Employers must provide information about the hazards, risks and control measures, and instruction and training to use the control measures. All employers must carry out a risk assessment and those employing five or more employees must also record significant findings. This record needs to be accessible so that safety representatives, inspectors, etc. can examine it.
You can find further information on working with hazardous substances in the HSE publication [Working with substances hazardous to health](http://www.hse.gov.uk/pubns/indg136.htm).