Most people in the CZ republic speak excellent English, also many are fluent in german too.. many english people go over there for medical treatment (dental, cosmetic etc), as it is better and cheaper than in the UK, so their medical teams will also be fluent in English too, so I can honestly say you would have no worries on that score.

My ex bf's parents didnt speak a word of Czech when his fathers job meant a transfer from the UK to Prague, but they soon settled in, and its very easy to pick up the language too.

All restaurants have english menus, and because of the increase in british people going there as tourists, you would be hard pushed to find anyone who doesnt speak english in Prague itself.