Rather than using the Bullet behavior, you can do that more easily IMO using the event sheet :
Set your player's angle toward the touch position, then use the "move forward" action. Set the distance to the speed times dt.
This will move the player at constant speed, if you want an accelerated movement I would implement it using the mathematical formula for acceleration and deceleration, or you can use the CustomMovement behavior to achieve that.
In my implementation, I would create a sprite for the player character and pin it to my (invisible) player object (which will be rotated). It is usually a good idea to do this separation, however, you can avoid rotation by using something like "move at angle" where the angle is computed between the touch position and your player's position (use the angle system expression to get the angle between two points).