For ww1, you might consider this scenario: more forceful state intervention in the war industries to make them more efficient then IOTL, with earlier formation of Ministry of Munition, earlier invitation of industrialists and technocrats into Cabinet and Ministry of Munitions. And if Haldane could avoid the Gallipoli disaster, he might not even need to form a Coalition, thus butterfly away the first Labour minister ever and prevent the slowdown of Education reform (well, IOTL, Arthur Henderson was basically useless as a Minister of Education).
I am not sure about Treaty of Versailles ITTL, but it might be still the same.
Next, after the war, a Liberal Cabinet that includes both Haldane and Lloyd George would be willing to spend money on public works and reforms instead of rolling back everything like IOTL.