Vodkaholic,
I have exactly the same orange pay as you go deal as you. If you go to the orange website, there is a sector about network cover abroad. You select the country that you are going to and a table will appear to tell you if your phone works in that particular country. I have found that is sim card does work in most countries in Africa, Canada and some Far East countries. I have now bought a sim card from maxsim(.co.uk) and works virtually everywhere. When I get a new laptop, I will just use skype.