It is generally held that an employer should meet an employee before making the decision to dismiss. If the facts prevent an employee attending, they should at the very least be given an opportunity to make representations before a decision is made.
In Charalambous v National Bank of Greece, a manager dismissed Mr Charalambous without meeting him. However, the appeal hearing provided a meeting between Mr Charalambous and the decision maker, and the Empoyment Appeal Tribunal found that the procedureal unfairness of not convening a meeting in the initial disciplinary hearing was sufficiently addressed by allowing a meeting at the appeal stage.
You must nearly always allow the employee to make representations at at a disciplinary hearing, and you should always seek legal advice if you want to deviate away from this approach.
If a procedural mistake is made early on, it can on occasion be rectified at an appeal stage.