Lightning War

Today in CWI, we watched a documentary about the start of World War 2. We learned that the Germans used a 'pincer' attack to attack Poland. The pincer attack was designed to surround and essentially crush the enemy. The Germans were able to surround and capture Poland in about four weeks. Next, the Germans went on to attack Great Britain. This went on to be called the "Phoney War" or "sitzkreig. It's called 'phoney' because nothing really happens in the winter except training the armies and trying to stay warm. The British kept using their strategies from World War 1, which obviously didn't work and needed improvements. Likewise, the British thought the Germans would use the same strategies from World War 1, which they most definitely were not doing. Something that confuses me is, wouldn't the British know about Germany conquering Poland by using new tactics? So, wouldn't they know to be prepared for the Germans to use those tactics in trying to conquer them(the british)?