Hi again kliro:
Having seen your update, it seems as though it will all hinge on whether or not there ends up being a "victim" in all of this. You say that the Police cannot contact the other party? That's not bad news, for you. It is possible that it may all be dropped.
However, it may well be that the opposite view is taken where it's deemed to be "in the public interest" to bring prosecutions, because, like it or lump it, it appears as though you were guilty of some kind of Public Order offence (there are many).
You mention "a caution or a fine". All I would say to you is this: A caution requires and admission of guilt. But you say you cannot remember what you did, therefore, technically, you couldn't admit guilt. However, that's a matter for you.
The worst scenario is either a caution or a charge, either of which would leave you with a criminal record.