He did notice, both before and after. Later he was informed by colleagues that the raid team caused the mess. That explains why they destroyed the audio tape gathered from the phone line.
Neville had a comminuted fracture to his upper humerus caused by the shots he received upstairs. So how can he possibly have got into a brawl in the kitchen?.
If your wondering what a comminuted fracture to the upper humerus looks like.

41.
Nevill Bamber, who was wearing his pyjamas had been shot eight times. There were two wounds to the right side and two to the top of the head. If not immediately fatal, the combined effect of these four injuries would have been immediate unconsciousness and incapacitation. There was a wound to the left side of the lip and another to the left part of the lower jaw. This injury caused severe fracturing of the jaw, of the teeth in that area and damaged soft tissue in the neck and the larynx. These features of this particular injury and the resultant flow of blood into the mouth meant, in the pathologist's opinion, that Nevill Bamber would not have been able to engage in purposeful talk. There were also gunshot wounds to the left shoulder and a grazing wound above the left elbow.
42.
The examination of Nevill Bamber's body also revealed black eyes and a broken nose, linear bruising to the cheeks, lacerations to the head, linear type bruising to the right forearm, bruising to the left wrist and forearm and three circular burn type marks to the back. The linear marks were consistent with Mr Bamber having been struck with a long blunt object, possibly a gun.
You're right. There may not have been a big fight. Although the judge said Nevill 'put uo a tremendous fight for life'.
However Nevill had got downstairs and Bamber was not going to hold back.
I suspect Nevill tried to grab the rifle which resulted in the scratch marks and smashed ceiling light.
When Bamber had control of the rifle he hit Nevill with it. Which explains Nevill's arm & wrist bruises & broken watch as he defended attacks to his head.
Once Bamber got through the arms, Nevill's face was next. His face injuries being horrific which would have knocked him out.
Bamber was then free to fire more shots, position Nevill on the coal scuttle and burn Nevill's back.