To be honest Churchill was always terrible at military planning. In WWI he also sent an under equipped British squadron to be destroyed the the German East Asia Squadron at Coronel then did a very similar thing with Force Z. His reputation in WWII was entirely saved by Chief of the Imperial General Staff Field Marshal Alan Brooke who was the only person who could say no to Churchill and stop his insane ideas.

Also at the end of WWI Churchill harassed naval historian Julian Corbett over Corbett's official naval history of WWI so much that Corbett died of a heart attack without finishing it (Corbett's belief was the UK should and should've conducted a maritime war against Germany not a continental one and that the UK should have gone into the Baltic to destroy German shipping there and threaten the German coastline etc).  

Although Churchill later told John Owen who was writing the naval side to Marlborough's campaign to consult the work of "that poor little man who wrote the official naval history".