There's a decent Wiki page on Britain's entry into WW1 here. [1] Britain's cabinet had already decided, before they chose to declare war, that the treaty did not obligate a military response.

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"Few historians would still maintain that the 'rape of Belgium' was the real motive for Britain's declaration of war on Germany. Instead, the role of Belgian neutrality is variously interpreted as an excuse used to mobilise public opinion, to provide embarrassed radicals in the cabinet with the justification for abandoning the principal of pacifism and thus staying in office, or - in the more conspiratorial versions - as cover for naked imperial interests."

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Similarly many people were fully aware that Treaty of Versailles was foolish as it was being drafted. Its excessively punitive nature essentially precluded any sort of peaceful reconciliation, which should always be the goal at the end of war. You never know who your allies, or your enemies, will be in a few decades. History loves a plot twist.

[1] - https://en.wikipedia.org/wiki/British_declaration_of_war_upo...