Lizard always thought that, everywhere but the US (i.e. anyplace that doesn't embargo Cuban cane sugar), table sugar is the cheapest.
In the US, it's corn (excepting, mind you, feed-grade molasses, which is every bit as bad as Potter says--once you distill it, good luck cleaning that stench out of your still!)
I'm not sure what farming culture is like in the UK, but in the US, if one lives in a rural area, feed corn can be picked up cheaply. Lizard has never had anyone say anything about buying 20# or so, even though he hardly looks like a farmer! City dwellers can look for discounts on produce from time to time.
Incidentally, the cost of sugar is super cheap, compared to store-bought booze
...half of that kg sugar gets turned into ethanol
, which represents ~600ml of 100 proof/50% ABV booze after distilling losses. 80p sounds preety damn cheap!