That is the purpose of postage, to allow you to mail letters to anywhere in the world. The stamps of the country of origin of the mail are used for postage.
looks like stamps.
Its 70 cents for sending a letter to any country in the EU. So, I guess that goes for England too.
Just sent one for £1.21. It was in a big envelope so a normal letter would probably be a few pennies less.
Right now the cost is 94 cents for up to one-ounce letter. On May 11, the price goes up to 98 cents.