Shipping is charged at Royal Mail rates.
Your product will weigh a certain amount and take up a certain volume. Our staff have built a very clever piece of software into this website that will calculate the charge based on the contents of your basket. It can do that no matter where you are in the world so you will be charged the exactly correct amount of postage!
My shipping says £x.xx and then suddenly jumps when I reach the final checkout screen! What gives?!
That's a known bug inherent in the cart software and is, at present, beyond our power to fix. You'll always be shown the actual shipping cost before you click to go through to your payment provider. If you're not happy with that price, don't proceed to PayPal and you won't be charged. :)