I'm not too familiar with the weights and speeds of the A340, however, if an error of similar proprtions, say 275 against 375 tonnes, was made to the aircraft I am familiar with, the 737-800, 55 against 75 tonnes, I am sure the 24kt difference from the normal V1/Vr would have been glaringly apparent. I might not be folwing SOPs strictly here but one of the first things I do when I sit down is to compute in my head an approximate Vr for the estimated weight and set that in the MCP panel. (It is almost always in the 135-155 range) If the speed later computed by the FO is more than a couple of knots different from that which I have in my window, I will get both pilots to re-check the calculations.
I'm afraid the Captain cocked up good and proper. If he was unduly fatigued, then stay in the hotel, call in sick and accept that you will be having tea and biscuits back at HQ. In future, Captains will be able to quote the experience of this unfortunate Captain when they have a similar sleep pattern.