I think the possible break out can occur downwards. Since the pole 310 - 380 is upwards and the channel is also moving upwards. Hence it would be better to trade at the channel support and resistance level. Once the either side break out occurs it will re-try to touch the trendline at that time you can initiate the trade. For downward break out first target will be near 330 second near 315.
My view it is not a Flag pattern simply because flag patterns are small maximum 15 bars in Flag formation. Please refer the book Encyclopedia of Chart Patterns by Thomas N. Bulkowski a great book to learn classical chart pattern. With best wishes