The first thing to note is that being placed on suspension is not an automatic assumption of guilt and does not amount to disciplinary action. It is there to be used as a precautionary measure whilst an employer investigates any allegations against the employee. Reasons for suspending could be in the case of gross misconduct, breakdown of relationship, risk to an employer's property, their clients or other employees, to preserve evidence or ensure it is not tampered with, avoid potential witnesses being pressured or intimidated, etc.
During the period of suspension the employer should conduct a reasonable investigation into the allegations against the employee. If the investigation gathers enough evidence to justify the taking disciplinary action that could be the next step. In that case the employee has the right to be informed in advance of the allegations against them and be given the opportunity to prepare for the hearing.
On the other hand, if the investigation does not find enough evidence to justify a disciplinary, the employer should terminate the suspension immediately and allow the employee to return to work as normal.
If the meeting was just an investigatory meeting then legally there is no specific time frames for providing notice or information before the hearing. They can just be told to attend with no notice. It is the formal disciplinary hearing at which they must be given details and information about the allegations. You say this has turned into a disciplinary hearing but that may not be the case in reality so it will become obvious in time, once it becomes clear where they are actually taking any formal action as a result of that meeting, such as warning, dismissal or other sanction. Also for an investigatory meeting there is no legal right to be accompanied, only at a formal disciplinary.
These people will have rights in terms of protection against unfair dismissal as they have more than 2 years’ service. This means that to fairly dismiss them their employer has to show that there was a potentially fair reason for dismissal and that a fair dismissal procedure was followed.
According to the Employment Rights Act 1996 there are five separate reasons that an employer could use to show that a dismissal was fair: conduct, capability, redundancy, illegality or some other substantial reason (SOSR). The employer will not only need to show that the dismissal was for one of those reasons, but also justify that it was appropriate and reasonable to use in the circumstances. In addition, they need to ensure that a fair dismissal procedure was followed and this would depend on which of the above reasons they used to dismiss.
If there are any doubts or evidence that the above requirements have not been satisfied, an appeal can be submitted to the employer straight after the disciplinary outcome is communicated. If the appeal is rejected and assuming this resulted in dismissal, a claim for unfair dismissal can be made in the employment tribunal. The time limit to claim is 3 months from the date of dismissal and the claimant needs to have at least 2 years' continuous service with that employer. Alternatively if they are not dismissed but they believe that they cannot continue working there any more as a result of this, they can consider resigning and claiming constructive dismissal instead.
I will also ensure that the phone call part of the fees you paid is refunded as I will not be able to fulfil this because we cannot find a mutually convenient time. Thanks