Just started off a DJ of this, had to add a lot more sugar than suggested, though I used brewers sugar. I used:
300g ginger
1 Lemon
1 Lime
500-600g brewing sugar
1 tsp Cream of Tartar
1 heaped tsp yeast nutrient
1 tsp Wilkinson's Ale Yeast
og ended up around 1.042 with a load of stirring...