It is not a requirement that details of procedure should appear in the policy statement, though it might be helpful to attach a schedule which has that information.
The important objective should be to keep it simple. The purpose, after all, is to establish what is in the best interests of the pupils and of the school. Although a panel of governors is not a court of law - and should not be treated as if it were - its activities could become the subject of legal review and so should conform with requirements of natural justice.
I recommend something along the following lines. The chair welcomes the appellants, introduces those present and explains the procedure to be followed. The appellants are asked to state their case, presenting any evidence on paper or through witnesses that they wish. The representative of the school and the members of the panel may ask questions. The representative of the school presents its case, similarly presenting evidence as appropriate. The appellants and panel members may ask questions. The panel withdraws to consider its decision, to be announce either at once or later as previously agreed.
It is important that all documentary evidence used in the case should be available to both sides.