question about traveling in Europe alone with a child

monkey_pants

I'm an American living in London and in a few weeks am traveling with my 2yo DD to Prague.  My husband is going a few days before us so it'll just be me and her.  When I've flown from NY to Toronto alone with her, I've been asked to show a notarized letter from my husband stating that it's ok for me to take her out of the country.  Does anyone know if I'll need the same thing here?  TIA...