It is possible to break down sucrose into fructose and glucose by boiling sugar with a tiny amount of acid (citric acid would do) the result is called invert sugar.
It is a bit of a faff though and could involve a couple of hours boiling to get the solution up to temperature and through to conversion. The result is similar to Golden Syrup which is largely invert sugar [approximately 56% invert syrup, 44% sucrose] in a convenient tin. Golden syrup is used by some brewers.
Whether you use the cheapest form of sugar or some sophisticated form [say, malt] is largely a matter of taste. The end result, production of ethanol, will always be the same.
If you like your ethanol tasty search out the sugar to suit the size of your wallet.
Of course sugar is rapidly becoming perceived as 'the new evil'. A sugar tax has been proposed. In the future there might be no cheap sugar. Finding a source at an affordable price in ANY form might end up being a big deal.
hoptimism - the realisation that each pint carries you forward to an ever more perfect ale...