What's the basis of the TV adverts promoting smart meters that say you will save money? Utter tosh!
The only thing that smart meters do is to provide homeowners with an in-home display that shows how much energy you're using and how much its costing at any given time. We used to have something similar with the old electricity meters, remember how fast the wheel used to spin when you switched the immersion heater on?!
Now forgive me if I'm being thick, but, surely if you've got an ounce of common sense you know what appliances are going to cost you money (eg led light bulb vs electric fire), and you use them accordingly - no need for a digital read out to tell you (and by the way, that is also using electricity all the time it's powered up!).
I had smart meters a couple of years ago purely for my own convenience when I was undergoing prostate cancer treatment, the in home display was quickly consigned to the pantry and wasn't used. Unfortunately I lost the smart functionality when I changed supplier (that wasn't very well thought out by the government was it?) and they keep promising that all these type of meters will be upgraded to once again make them 'smart', although the timescale for this keeps slipping and is currently the end of 2020.