As a Scientist I have travelled extensively all over the world. The most general thing I can say for Europe is that you should have little trouble in larger European cities where the population is more 'cosmopolitan' and English is usually either a second language or picked up from the barrage of American media they are exposed to. Once you leave the big-city areas however, it gets a little more diffcult and you have to play a game of 'Charades' sometimes to get your point across.
Good thing I am with a tour group. Our priest is leading it!