Well this thread has been an eye opener.
My plan was to use a funnel and a small measuring cup with 4g of priming sugar per 500ml bottle. I have been worrying about any damp clogging the funnel and was going to try to solve this by drying the cup, funnel and tops of bottles with a hair dryer after sterilisation to ensure everything is bone dry. Not sure if that would have worked, but can't see why it wouldn't, has anyone tried that before?
Now I have read this though, I am thinking I will just dissolve my sugar in water and use an old calpol syringe. 160g sugar in a measuring jug, topped up to 200ml of water to dissolve will give me 4g sugar for every 5ml portion.
Pretty sure I have my maths correct on that?