Neville Chamberlain died on 9 November 1940 - six months after his resignation as Prime Minister. He was diagnosed with terminal bowel cancer in July 1940.

A few days before his death, he wrote:

So far as my personal reputation is concerned, I am not in the least disturbed about it. The letters which I am still receiving in such vast quantities so unanimously dwell on the same point, namely without Munich the war would have been lost and the Empire destroyed in 1938 ... I do not feel the opposite view ... has a chance of survival. Even if nothing further were to be published giving the true inside story of the past two years I should not fear the historian's verdict. ( Self, Robert (2006). Neville Chamberlain: A Biography. )

Great Britain wasn't ready for war in 1938, so Chamberlain really didn't have many options at Munich. The country started preparing for war in 1938 (e.g. increasing output of Spitfires and Hurricanes), so I suppose that Chamberlain bought them some time, if nothing else

TL:DR He didn't have very long to reflect, and he didn't seem to have any regrets.

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