You'll have to get over that paranoia. People will always do that, even in nominally English-speaking countries.

In general, the larger the country is, the less chance there is that a random person you meet on the street speaks usable English. Germany, France and Spain are particularly bad in this regard. I don't have hard numbers, but with very wide margins, you might expect that >95% of the working population speaks English in Scandinavia but only 50% in France.

So go to Sweden, if you have the option. Scandinavia's the nicest area of Europe anyway.

That said, emphasis on "random" above. Anyone working for a university is almost guaranteed to be competent in English, especially in a technical area.