No, Mrs D, I am not woefully uniformed, any more than you are being hysterical. We just see things differently. I am advocating a risk-benefit analysis. Not discounting others' risks, but trying to calculate them, and putting the OP's benefits into the equation.
The OP was proposing taking a quick trip with two small children in a pushchair who have CP, covered with a rain cover, one outdoors to do the school run and one into a supermarket to get bread and milk. The NHS advises very vulnerable people who have been in close proximity for 15 minutes or more to contact their GP. None of that is going to happen. As already mentioned, if CP is doing the rounds, the odds are that vulnerable people will be exposed anyway. The additional risk is tiny, though the consequences are huge.
Against that, the OP's DTs are confined for another week when they have already been confined for 2 - with the risk that they will suffer anxiety, agoraphobia, and desocialisation. I put to one side the further risk that the online shopping driver might run someone over on the way to deliver the shopping, probably (depending on what sort of area the OP lives in) a greater risk to life than the one that you think the OP should avoid. I am sure there are other risks, too.
With all risks, you have to set the benefits against it. Otherwise, none of us should cross the road unless to save a life, or get in our cars to drive somewhere, or go outside our bubbles at all. This is what H&S cultures do - they assess the risks and forget the benefits, and often do not assess the risks of the opposite course of action at all. And consequently, sports days are cancelled, trips do not go ahead, and children sit inside terrified of a hostile world full of risks (and untold benefits).
Clearly some emotions run very high here, and as was said originally, there are very entrenched views. I am certainly never going to change mine on this issue, will maintain that those who have not had CP should be vaccinated if they plan pregnancy, and that a quick trip to a well ventilated supermarket with DTs confined to a buggy with a rain cover over the top is not an unreasonable thing for any mother of four to do.