Hello, I am a solicitor with 20 years experience. I will try to answer this for you.
Is this a police interview? When will it take place?
Ok this will probably be police interview. She must have a solicitor. I can not emphasise too much how important this is. You cannot trust the police to be truthful with you. Your only chance to find out before the interview the nature of the allegation ( and then probably only just before the interview) is through a solicitor. Representation at polic interviews is free and you can have either a duty solicitor or choose your own solicitor free of charge.
You must realise the purpose of the interview is not to clear things up or to get your daughter's side of things. It is to gather evidence to use against her. She is also entitled ot have an "appropriate adult" present when she is being interviewed. This is usually a parent.
Use this link to find a local criminal defence solicitor and call them. Most will talk free of charge and liaise with the police for you.
If the police investigation leads the CPS to think that there is sufficient evidence to have a better than 50% chance of securing a conviction and that it is in the public interest to prosecute then your daughter could be charged and there could be court proceedings and ultimately depending on the evidence a conviction.
Your daughter is young and her details will be kept private. It would only be in the most serious cases (which this does not sound like) that any significant punishment would be imposed on your daughter.
Social services may well be interested especially if there are younger siblings. That side of things is a bit outside my area but I would expect regular meetings with a youth social worker for a period of time dealing with whatever issues arise.
The likelihood is that in a not very serious offence the sentence would be very similar to the action to be taken by social services with the emphasis on education and addressing issues. The court system has a duty to prevent re-offending and to keep the welfare of your daughter at the front of their considerations.
That's fine. I would be grateful if you would rate my service as I will not get credited for these answers if you do not do so.