During the launch by a tug aircraft for the pilot's first flight of the day, turbulence was encountered at about 40 feet agl. The pilot released from the tow and attempted to land straight ahead, however the right wing struck a post of the aerodrome boundary fence and the aircraft ground looped before coming to rest. The pilot had earlier experienced difficulty in fitting the all-moving tailplane to the glider during the pre-flight assembly. Shortly after becoming airborne the turbulence led the pilot to believe he had elevator control problems and he released from the tow. He then planned to land straight ahead, controlling the rate of descent with the air brake and making virtually no elevator movements. The use of air brake shortened the gliding distance to the point where the aircraft could not clear the boundary fence. Subsequent investigation revealed no defect with the elevator controls or the tailplane.