I think a neutral viewpoint on this would be:
The female presenter made a number of claims including a phone call from Mr Bamber Snr to the police;
Nevill could easily have made a call to the police, the question is specifically whether he got through to them and spoke to them. I believe it is unlikely as there would be no reason for the police to conceal a record of such a call and the investigation would never have focused on Jeremy in such circumstances. There is a small possibility that a telephone operator did speak to Nevill and in all the confusion has conflated one call with another, but again, it seems a stretch.
There is the additional possibility that Nevill did make a 999 call but was injured and could not talk into the phone.
Sheila making a 999 call and writing a suicide note 'I have just killed myself';
They have not claimed this.
Sheila observed by the Aga and running up the stairs to shoot herself once;
Well a female was observed in the kitchen. The official story is that this was a mistake and that the mistake was quickly corrected. It's a whole discussion in its own right. One ground for questioning the police story on this topic is that they are recorded as spotting both a male and a female at the same time in the same part of the house through a window.
the police shooting Sheila a second time,
There is no physical evidential bar to this, on the condition that you accept the 'swopped bullet' theory. Personally I believe the swopped bullet theory is flawed, for reasons I have gone over on other threads. It falls apart under closer scrutiny.
the police using the crime scene as a training exercise,
I simply have no idea if this is true or not, but why shouldn't the police exploit the crime scene for training purposes? It seems like a good idea to me.
Robert Boutflour's blood contaminating the silencer.
Very plausible in my view.
Can someone provide me with any evidence to support these allegations?
No, or rather, the evidence for these allegations is already canon. It's a matter of how you interpret the evidence and what inferences you choose to draw.
It is interesting how one camp is very quick to draw all sorts of inferences about Jeremy, including that he is a mass murderer and double child killer - just for money - while ignoring all the fantastical prerequisites for the execution of such a criminal plot.