Time to command is a variable feast. Obviously dependent on various factors including, but not exclusivly, the retirement age, fleet expansion, Gatwick expansion, Heathrow third runway and what happens with the tie up between BA, Iberia and American. Currently expect the wait to be in the region of 10-12 years SH and up to 17 Years LH. Don't forget though that the current FO pay scale slides a long way up especially on the LH side so, financially, the wait isn't too strenuous.
AFAIK the 'sim' involves only the sim check but expect to be 'quizzed' at least a little on your decision making thought processes.
Good luck