I'll do that and send it over to you, I'd really like to get some advice from someone who knows what they're doing, and by the sounds of it, you're that person. Hopefully the Irish one isn't too different.
I really appreciate the advice and a lot of this makes sense. I think what I need to do is bring an item down to the post office and ask them to weigh, measure and tell me the price for sending to America, Canada, UK and Australia. Mainland Europe would be good too, and from there I can come up with a happy average where I'm not ripping buyers, or myself, off.
Luckily the only things I'm selling is games, and it seems to be about 160 grams, 18x14x3 CM, and those dimesions don't seem to change from item to item.
Good shout on the signed shipping too, I'd be much more comfortable for that being the norm when sending out items. I've heard of some scams, and makes me weary, especially knowing the price of some of the games I'll be sending out.