It's basically saying, do the things you're already been told to do or, if we catch you, you'll be asked to stop whatever it is you're doing wrong. Then we might fine you.
Friends elsewhere in the world have said their lockdowns include things like documentation which needs to be filled in each time you leave the house, only 10 customers at a time in large supermarkets, no dog walking, no outdoor exercise. What we've just been told to do is basically the same as what we've already been told.
I wouldn't be surprised if the same arses who didn't listen last time don't listen this time and in a few days we'll have the even more draconian measures seen elsewhere. Might've been better if he'd just got straight on with it and done it now, then we might get through this just a little bit faster with less strain on the NHS and fewer deaths.