Can I suggest that all you contract pilots read the thread regarding tax and easyjet in Germany?
It is also wrong to say that it doesn't matter where you pay tax. You are obliged to pay tax in the country where you derive the majority of your income. Essentially, that means that if you work on a contract for Ryanair or Easyjet and are based in Rome or Bergamo or Hahn or Berlin then you must register with the tax office where you work. It makes no difference if you are English, French or whatever.
Avoiding tax is a fraught and dangerous past-time.