See a CAB/lawyer but basically there are two concepts you need to get your head around:
Burden of proof - ie whose responsibility it is to prove something. In criminal cases it is the Crown (Prosecution) who have the burden of proof ie they have to prove the accused is guilty, s/he doesn't have to prove they are innocent. In civil cases it is the person who brings the case to court who has the burden of proof.
Standard of proof - ie how persuasive the evidence needs to be.
Civil cases normally operate to a standard of proof that is 'On the balance of probabilities' ie which account is the more probable to be true. There can be significant doubt as to whether the losing account might be true and it still be found to be more probable that the other account is correct. Sorry, that's not worded too clearly, I'm just saying that the evidence in a civil case doesn't need to be watertight.
Criminal cases normally require the case to be proved 'Beyond reasonable doubt' ie would a reasonable person accept that the evidence established guilt or might the reasonable person be doubtful of guilt because the defence had shown there were 'holes' in the prosecution's case.
You can see from this that the civil standard of proof is easier to meet.
If you are taking a case against your employer then the burden of proof lies with you to establish your employer did what you are complaining about. You will almost certainly need to establish this to the civil standard ie 'on the balance of probabilities' but this is where my knowledge runs out and you need to check with someone qualified. My gut feeling is that the reference to the standard of proof is just a formulaic inclusion.
As to how much compo, you definitely need advice, people tend to undervalue the damage they've suffered. Many CABs have advice sessions with local lawyers, check it out.