OK. Harry you have to make a similar looking part.The pic below. It is a part of airfoil called "nose". As you might noticet is of the same shape like the wing.
I suggest to use a thin cardboard for getting the model wing shape at the gap area. Simply take a rectangular piece of the carton and apply it with fingers to the side edge of the hole for the light. Draw outside with a pencil going along the wing curvature.Then cut it with your sccisors. Copy the shape on the plastic plate but add 3mm to that part at the rear area. Remember that the 3mm of additional length go into the wing inner space.So its hight there has to be diminished of the thicknes of the wing halves.Also drill two circled holes to imitate the inner structure of the wing element.