Agree that India was ready for independence.
Jamaica is interesting. Marcus Garvey, Alexander Bustamente, and Norman Manley are interesting figures of the time. There was a labor union movement. Maybe Jamaica would also have seized the moment to declare independence.
Malaysia doesn't seem very unified in the late 1930's. There are several small states, along with ethnic and religious divisions. And there's Thailand looking for a chance to regain control of some of the small states in northern Malaysia.
Reading further, Egypt was already independent from 1922, and Iraq from 1932, though both continued to host British military garrisons. I can see those garrisons, along with the garrisons of India, returning to Britain to fight in the civil war.