The pilot reported that he was making his first flight in his ultralight which he had just completed building. After a 30 minute flight around his farm he made a landing approach to a grass strip. The intention was to overfly the strip and make a left circuit. However, as he crossed the threshold he judged that he was in the right "slot" for a landing and the approach was continued. But when the aircraft was in the flare he sensed the heading to be 10 degrees right of the strip direction. Because of lack of recent flying experience, he decided at that point that the safest thing to do was to abandon the landing attempt and go around. Confident that he had plenty of reserve power he did not use full throttle for the go-around. As power was applied, the right wing dropped gently, not responding to aileron. The pilot assumed a control malfunction and was not prepared to open the throttle any further. The aircraft continued to turn to the right, now heading toward a power line that was running parallel to the landing strip. The pilot instinctively applied backstick to clear the power line but the aircraft continued the uncontrolled gentle turn to the right. The pilot said that "resigning himself to the inevitable" he began closing the throttle. The aircraft gently descended into a stubble paddock. The pilot advised that he later realised that a mild stall had developed on the right wing and had proper stall recovery technique been applied, the situation would have been corrected. The pilot subsequently critically self analysed the accident and identified a number of factors that resulted in him being under significant stress while performing this first flight in his aircraft. In hindsight he believed that he should not have flown the aircraft at all until he had completed some dual flying.