UK police can be prosecuted for risking their own life

If I read this right:

The report says police officers 'may, very occasionally in extreme cases, decide to put themselves at risk in acts of true heroism'.

In these 'rare circumstances', the HSE adds, 'it would not be in the public interest to take action against the individual'.

So a cop, who can be prosecuted (in the name of safety) under the law for risking his or her own life can make a "personal choice" not to violate the law and attempt to stop a crime? So, faced with one of two choices:
1 Do nothing
2 Risk life to prevent a crime, thus leaving oneself open to possible criminal prosecution

Which do you think a cop would choose? Why does the UK even BOTHER to have police? All of this in the country where weapons are illegal, as is self defense, and crime is skyrocketing.

I can hear Churchill now:

We shall defend our island, whatever the cost may be, we shall fight on the beaches, we shall fight on the landing grounds, we shall fight in the fields and in the streets, we shall fight in the hills; we shall never surrender, unless of course, fighting was unsafe. Each soldier and citizen may have to decide at some point not to risk his life, and we support that.

If, however, the soldier feels the risk is justified, then we would certainly look at the facts and decide whether or not to be lenient and not prosecute.