Going to the British Grand Prix at Silverstone

I am going the Silverstone for the 2nd time this year and am wondering where you would find the drivers to sign autographs. I can’t find any ‘Paddock Passes’ although the North pass gets you into the Support race paddock. I’ve heard that lingering around the paddock entrance is a good shot but I am looking for where the autographs sessions are organised. Maybe someone can tell me where they were last year if they don’t know for 2014?. Thanks in advance.