Buy it and stockpile it at todays rates. Post Brexit if no deal there may well be a hefty tariff on sugar, and although unlikely, it might go up by anything up to 30% next year.. Have forward contracted my supplies at a decent price till the end of 2019. (£330/mt btw, but that's in 1.2t bulk bags in full truckloads...not particularly relevant to most.) In other amounts anything under £400/mt or 40p/kg is a pretty decent deal. So HM is doing just fine.
Of course the price might also go down, but todays rates are at a level that is very attractive and any further falls may well only be small. So have placed my chips and happy at that.