NP2WENTY6 - shipping abroad isn't that much harder than shipping in the UK. When I first started selling on the internet I invested in a small set of digital kitchen scales that go up to 5kg . Since then I have had to invest in a larger set so if I get really really big items I can still weigh them.
In a basic spread sheet I the actual amount it would cost to post in a item and in another column, with use of an equation I work out how much I would charge to sent relevant items to include the cost of packing. When the PO decides to change the cost of postage I just need to put in the new amount of postage and the computer will work out how much I would then charge.
I have a another spread sheet for both printed matter and other items via airmail. Again releveant costs can be worked out.
So when I am getting ready to list I can weight the items (on the scales) and leaving a bit for packaging I can easily look up on my printed forms to see how much I should enter for P&P. A little preparation can go a long long way in the long run.
If you are a little worried about posting abroad try just posting to Europe as less paperwork is needed. It does get easier the more times you do it.
My little set of scales was well worth the investment - at least I have a very good idea when I am standing in the huge huge PO queue that I know there should be few surprises. Even the counter staff now know I now what I WANT and they have to ask less questions every time.
Saying that I have yet to make an overseas sale here - but I'm hoping and I do post to Ireland. You just have to look in these boards to see how far folks are based.