To be technical, George Orwell did not always write about Communism. Orwell's themes were really directed against imperialism that he saw while living and working in Burma as well as his dislike for totalitarianism that he experienced and wrote about in his works against Stalin.
Orwell wrote very early about how he felt about being in Boarding Schools in England. He was born in India but his mother brought him to England very early in life. One of his writings was about his life in poverty as he took odd jobs around England and France. Orwell also worked as a teacher for awhile.
George Orwell's real name was Eric Allan Blair and his political leanings were Socialistic. If he saw an injustice he wrote about it. He wrote against the lack of integrity, responsibility and politics. His famous work, Animal Farm, was an allegory against the totalitarianism of the Stalin government in Russia, and his novel 1984, was also written to warn people of what could happen if they let themselves be controlled by totalitarianism.
"By that time, Orwell clearly saw himself as a political performer whose tool was writing. He wrote in a 1946 essay, “Why I Write,” that “every line of serious work that I have written since 1936 has been written, directly or indirectly, against totalitarianism and for democratic socialism, as I understand it.”
But in a sense wasn't the books really directed towards Communism and Socialism then.