It is the single use one which I will need for France - I will get one when I am in England in May. We are being given a few months' grace after the law takes effect, when the gendarmes will just give us a warning. We already have to carry high visibility vests which have to be kept in the body fo the car, not the boot , two warning triangles and spare bulbs/fuses (which would be useless anyway, as most headlight bulbs can only be replaced by a garage). I also have to carry chains when there is snow or ice on the road.
I don't like the idea of the breathalyzer- if you have to check your reading you should not be driving. They probably won't stand up in court because they are not regularly calibrated.
Meanwhile, I see drivers with dogs on their laps, and mobile phones glued to their ear, so I expect French drivers will just carry on as they always have.