I continue to wonder about the process where British forces were sent to Greece in 1941

If you believe Churchill, he could have been dissuaded from sending troops to Greece in 1941, if the commanders had objected. The reason why I might trust that declaration is that as soon as Churchill was notified about Greek concerns about heavy fighting, he ordered the British withdrawal. I think that much of the responsibility for the failed adventure lies with General Wavell. General Wavell was trying to be the "good soldier" and do whatever the politicians wanted, regardless of the consequences. The result of proceeding with the operation not only were the loss of men and, especially, equipment in Greece and the near-loss of the North African position, as well. If the Greek adventure had not proceeded, Rommel could have been stopped, during the February-March 1941 timeframe.