Sennadog, the incidents you describe do sound like bad manners/poor lookout, but one thing to bear in mind is that it can in some circumstances be safe and appropriate not to fly the circuit in exactly the way that you do when learning. What may seem to a student or low hours PPL to be cutting in may be a faster aircraft overtaking safely.
. .At Waltham, which, as pointed out above, operates excellent by the book A/G, you sometimes hear people flying wide downwinds gripe about aircraft joining from overhead and quite legitimately positioning for a tighter downwind ahead of the other aircraft. I once heard a slow aircraft announce that he would, quite sensibly, make one orbit in circuit direction on downwind, to allow a fast complex to pass him. The complex then complained of an aircraft flying the wrong way in the circuit nd threatened an airprox, which was nonsense. The point here is that the pilot in the slow machine was using eyes, ears and judgment, the other one was simply following his set way of doing a circuit, and not even paying attention to other people's transmissions.
Another point is that, as Girl Flyday has observed on the other airmanship thread, see and avoid is no guarantee of safety: anyone who says that he/she has never been surprised by another aircraft hoving into view at closeish range is either fibbing or has Superman-vision and reflexes.
As for filing mandatory reports and so forth, I would suggest that, unless something very dire has occurred, you might be better off filing a CHIRP. These are often followed up and do achieve results, for example in relation to A/G or FISO operators overstepping the boundariers. A system which does not operate on the blame culture can sometimes be more productive of positive change than one which forces people onto the defensive.