Leaving aside whether you are guilty of an offence or not, you should be served with a notice of intended prosecution (a NIP). This should be posted so as to arrive, in normal circumstances, within 14 days of the alleged offence, and is usually served with the request for the driver's details.
You say that you have received no such notice, but you are aware that you have been reported for an alleged offence. Although the paperwork you have may not say "Notice of Intended Prosecution" it will almost certainly be argued that the documents you received informed you of the possibility of prosecution. You may therefore have difficulty arguing that no such notice was received and I believe you should assume that a NIP has been served.
That being the case, as has been said, the posecution has up to six months to bring the matter to court.