Opinion polls seem to show a narrow majority in favour of the government's proposed ban on smoking outside pubs. The correlation seems to be that if something is potentially unhealthy and costs the NHS money (irrespective of the revenue raised from it) the consumption of it should be restricted, or ideally banned, a dangerously authoritarian idea which could easily be applied to many other things, especially those already deemed harmful by public health professionals, notably alcohol and fast food.
The original ban on smoking in indoor spaces could be justified by the protection of others from the effects of passive smoking, in particular pub staff, but that doesn't apply here. It's hard to see any other motivation for it apart from middle class distaste for and disapproval of unhealthy working class habits.
If this ban goes ahead, one of three things will happen: smokers will stop going to pubs, the time and money spent on constructing outdoor areas for them there will have been wasted, and inevitably more will shut, especially wet led ones; smokers will stand just beyond the boundary of the pub premises, potentially causing a nuisance to pedestrians and other businesses; or they will find the darkest corner of the beer garden in which to flout the ban, leading to awkward confrontations between pub staff and their customers who will rightly wonder what harm they are doing by smoking a cigarette outdoors and why that act is now illegal.