Since no specific proposals have been published, though, it's not clear that this is the intention. The reporting has picked up on a reference to "street harassment", taken one example of that behaviour, and run with it to an extreme.
The references I can find mention "new advice on *existing laws* for police offers to more effectively respond to street harassment" (p18 of my link earlier, emphasis added); and on page 71 a promise to "look carefully at gaps in existing law and how a specific offence for public sexual harassment could address those". This, along with a promise to encourage reporting of any harassment that falls under existing laws, and to study the roots of such behaviour in order to discourage harassment from occuring in the first place.
It is presumably clear that wolf-whistling is a small part of this, but the idea that it will become a specific and separate offence is an invention. In particular, whether or not a wolf-whistle is welcome, what would determine if a crime has been committed is the aftermath. If, for example, a woman takes no offence from being whistled at, then already that ends the matter; the State cannot take offence on her behalf. If, instead, a woman complains and is met with derision or abuse as a result, then it would be the entire package that was the offence, and the whistling only a contributing factor. And if, finally, a woman complains and is met with an apology, then the problem ends there.