You must tell each employee about:
your disciplinary rules
your disciplinary and dismissal procedure
the name of the person that they should appeal to if they are unhappy about a disciplinary or dismissal decision
You can either include this in their written statement of employment or refer in the statement to where they can find the information, eg in a staff handbook.
If you fail to provide this information to an employee and they succeed in an industrial tribunal claim against you, they could be awarded two or four weeks' pay.
The contractual status of disciplinary procedures
The statutory dismissal and disciplinary procedures may not necessarily form part of an employment contract. In this case, an employee may not be able to claim breach of contract if you fail to follow it. Any dispute over this will be up to the courts to decide.
If you do choose to make the statutory or your own disciplinary procedure contractual and you fail to follow it when taking disciplinary action, the employee could bring a breach of contract claim against you.