Badly played endgame leads to defeat

It was Sunday afternoon and the final game.  Having played 1.e4 as White I realised of course, that Black had the opening choice.  He chose 1. ..c6 The Caro-Kann.  Again, I'm not sure of the theory but I'm very aware that the standing joke in chess is that many Caro-Kann battles lead to draws!  There is a sharpish line that I have been advised to play by an IM in the London Chess Centre and that is the 'Advanced Variation' (1.e4 c6 2.d4 d5 3.e5 Bf5 4.h4 h5 5.c4).  Whilst I have had a lot of success with this variation in Blitz I wasn't confident enough to play it at this tournament.  Not sure why? -  Instead I elected to play the 'Classical Variation'.  I made one or two beginner's errors - For instance, taking the Knight on f6 wasn't entirely necessary - I could have simply played 6.Bd3 instead.  

Interestingly I thought I had the game completely wrapped up with a passed 'b' pawn that I considered unstoppable!  - Not the case :(   It turned out that I completely overlooked his 'unstoppable' capture of my pawn on d4 and his own threat of queening the 'd' pawn.  He ends up with a passed pawn and a won game.

1. e4 c6 2. d4 d5 3. Nc3 ( 3. e5 Bf5 4. h4 h5 5. c4 ) 3...  dxe4 4. Nxe4 Nd7 5. Nf3 Ngf6 6. Nxf6+ Nxf6 7. Bd3 Bg4 8. c3 g6 9. h3 Bxf3 10. Qxf3 Qd5 11. Qxd5 Nxd5 12. O-O Bg7 13. Re1 e6 14. Bd2 O-O 15. Bc4 b5 16. Bxd5 cxd5 17. a3 a5 18. Bf4 Ra6 19. Bg5 Rfa8 20. Be7 Bf8 21. Bxf8 Kxf8 22. Re3 b4 23. axb4 axb4 24. Rxa6 Rxa6 25. cxb4 Ra1+ 26. Kh2 Rd1! 27. Rb3 Rxd4 28. b5 Rc4 29. b6 Rc8 30. Kg3 Ke8 31. Kf4 f6 32. Ke3 Kd7 33. Kd4 Kc6 34. Rc3+ Kb7 35. Rxc8 Kxc8 36. f4 Kb7 37. g4 Kb6 38. f5 gxf5 39. gxf5 e5+ 40. Kxd5 Kb5 41. h4 h5 42. Ke4 Kb4 43. Kd3 Kb3 44. Kd2 Kxb2 45. Kd3 Kb3 46. Ke4 Kc4 0-1

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