You should receive 24 hours written notice of any disciplinary hearing and you should be allowed to take in a work colleague or a union official with you.
It all sounds like a lot is being made of workplace gossip to me and on the face of it does not sound like gross misconduct, so should not be a dismissable offence. Although obviously I do not know the full facts!
If your company intends trying to mismiss you for gross misconduct, they really should suspend you while an investigation is being carried out, if they do not do this, then you should have an automatic case of unfair dismissal.
If you are not allowed to bring anyone else in with you at a disciplinary hearing, then you may also have a case for unfair dismissal (if it gets to that) as I believe that this is your legal right.
If you think this is getting serious, then I would have a chat with a solicitor and let your company know you are doing so! A lot of companies do things incorrectly, relying on the ignorance of their employees to get away with it!
Hope this has helped
Sue