Mr. Palmtree,
AFAIK, Boeing recommends that the auto throttles be disengaged while hand flying an approach.
At this level of ones career, we must be able to perform basic functions of flying. That includes a scan, interpretation of said indications and acting accordingly. If you can't maintain airspeed during a daylight straight-in visual approach, I would suggest that you need more training, or may want to wait a while until you master such basic skills. If you're that inexperienced, you should not be flying 290+ people in a wide body.