No they are NOT just wanting to give a choice, and some of it may well be mandatory.
Note questions 1a and 1b on the consultation:
1b) Are there any specific areas that you think should be excluded from a choice in units of measurement, and why?
So they are entertaining the possibility of things being sold only in imperial (or only in metric) and if you respond to the consultation and answer YES to this question, that is what you are giving approval for.
1c) If an item is sold in imperial measures, should there be a requirement for a metric equivalent alongside it?
Again they are clearly entertaining the possibility of things being sold only in imperial. Even if you are in favour of that, think of others when answering this question.