Yeast will invert sugar to use it as energy by itself - you don't have to invert it yourself prior to pitching. Using invert sugar will make the fermentation start a little earlier, but it's not noticeable. Some invert sugars can bring different flavours to the beer, so it can be worthwhile using them for that reason. Tate & Lyle Golden Syrup is invert sugar, so use this if you want to. It can add a slightly toffee flavour to the beer.