Some tips :
Language : UK will not be problem of course. In most Western European countries (Scandinavia, Germany, Holland, Belgium, ...) , you'll be fine with English. In Southern European countries (Italy, Spain, Portugal, ..) it most of the time is a problem if you only speak English.
Of your list, Denmark and the UK are by far the countires with the most expensive living standard. Germany, Holland, Belgium, France, .. are average expensive to live, while Southern Europe is the cheapest to live.
The capitals and big cities will be in any case the most expensive to live, but the easiest to find a job.
Why not look for American multinationals searching for expats in Europe ?