Do what you want as long as it’s not harming anyone else.

The problem is that it does harm others. Not only in the obvious ways, such as passive smoking, the toxic chemicals that cling to smokers, the environmental costs, and such, but also the increased healthcare costs. The NHS is tax funded, and smokers add significantly to the cost of that.

Remember, this ban isn't stopping anyone who currently had legal access to cigarettes smoking, it is only stopping those who don't yet have access from gaining access. It's not actually depriving anyone of freedoms they already have, simply blacklisting a behaviour which has no positives and significant downsides.

Ultra processed foods are not good for human beings either.

Most of these mass issues aren't because "the people want it" its because corporations have pushed their products for generations and only care about money and not public health.