I had read on one of your earlier threads that you are located in NY just north of the PA border? If that is correct then it is getting a little late for oats. The oats are slower to sprout and grow than rye,triticale or wheat and you wouldn't get as much growth before the ground starts to freeze.
Same goes for the brassica mix, but you could take a gamble and "see what happens".
I have planted chicory both in the spring and late summer. I had much better luck with the late summer planting. Weeds can be a real problem with a spring planting. I planted the Puna II type with Alice White Clover and used oats as a nurse crop. Planted the end of Aug.