Usual process is:
An allegation is made
If it's serious enough, which it sounds like this could be, they'll suspend you. You should be on full pay during this time.
The suspension, as upsetting as it may be, is to protect you as much as whoever made the allegation and to also allow the process to be carried out fairly.
While you're suspended they'll investigate. Meaning they'll speak to any and all witnesses to try and piece together what happened. They'll want to do this fairly quickly, because it's costing them money you being at home.
At some point you'll be invited in to have your say. You should be told what the allegations are, or the incident etc, however they can't tell you who it came from. In my experience, it isn't hard to figure it out, however hard they try to keep things anonymous.
Once the investigation is complete, they'll decide on a course of action.
If a disciplinary is to take place, you'll be notified in writing and offered the opportunity to have a companion / union rep with you. Along with this letter you may be sent a copy of the investigation notes.
After disciplinary, there'll be an outcome. This may or may not be a separate meeting.
You need to understand that unless the person making the allegation agrees, they'll keep things anonymous and won't be able to confirm names.
While you've got this time off, have a think about who you'd like with you at these meetings. Want a union rep? Join a union if you aren't already a member.
Whatever you do, do not try and contact work colleagues to discuss or find out what is happening - you could be accused of trying to sabotage the investigation process and it won't do you any favours.
As hard as it is, sit tight. If you know what this is about, get your evidence together and stay cool, calm and collected.
Good luck