The violation of Belgian neutrality provided Britain with its official excuse for entering WWI. However, would it really have kept out of that conflict had things been otherwise?
Ever since the Jameson raid on the Transvaal (1895), British relationships with Germany had been deteriorating. These were irrevocably damaged by the 2nd Boer War (1899-1902) - a war in which Germany was always on the threshold of joining in as a belligerent. Afterwards, King Edward VII (“Edward The Peacemaker”) was able to shore up relations with France. That led to the Entente Cordiale with “The Old Enemy”.
However, anti-British feeling in Germany was by then so strong that he had no success in repairing damaged relationships with Germany. By 1914 (if not earlier) there was widespread feeling in Germany that armed conflict with Britain was in fact inevitable.
Also, being then the world’s dominant naval power, it is highly unlikely that Britain would have tolerated German possession of the channel ports.