There certainly was a scheme to help ex-service to train and/or qualify for things like teaching, after the war. Many went to University under ex-service schemes, and to Training Colleges, as they were called then, as well. There must have been been a grant scheme, and those dates would approximate to the start of terms, wouldn't they, so that sounds a very likely source of the income! Many of those teachers may have been shorter term trained, but the few I knew were very good teachers - often quite easy to sidetrack with What did you do in the War, Sir?" questions!