I obtained my licence in June this year. Last week I was asked to go to Little Gransden in Cambs to collect a part for another ac. Being in the South East I was not too comfortable with having to jink around London at short notice - this was too close to the edge of my envelope so I asked my instructor to accompany me. He did the nav and I did the flying and everything was ok until we called the airfield blind and stated our intentions. My instructor was aware of the glider site at Gransden Lodge however to my surprise, having started my descent on the deadside of runway 28 I was faced with a glider coming in the opposite direction although he/she was higher. We both took appropriate action and I continued in the circuit and landed safely. It was only when checking in at Little Gransden did I see the joining instructions which showed I should have not ventured north of the field. My fault entirely I admit but I would not say it was unprofessional flying.