Never been - but hoping to make it there tomorrow night and hope for a reasonable GS turn out?
As I understand it - I can get there via M25 J10, by taking the A3 away from London, then first left into Martyr's green, and apparently it's along there somewhere towards Effingham?
The turning you need is on the A3 slip road coming of off the A3/M25 interchange. Its just past a lorry lay by and cafe; you have to use the interchange.
The Black Swan is about 1.5 miles or so down the road, on the RHS at a crossroads.