Sudetenland was small enough to do not change things much from military strategy perspective. Bigger deal was Poland taking also minor part of Czechoslovakia, but also it didn't change much. It was hard to defend Poland anyway. But French and British could have marched mass scale into Western Germany, but they didn't, to not "escalate things" (same as in Ukraine now), French invasion was very limited. With Denmark and Norway Germans just did first strike, UK didn't have enough time to react. British could have occupied Norway first if they really wanted to.