A comical own goal by the left-back Neil Ashton handed the advantage to Bury ahead of the second leg at Gigg Lane, but Simpson is convinced his side can go to Lancashire on Sunday and secure an aggregate success.
"I thought it was a fantastic game of football and a goal like that didn't deserve to decide it," he said.
"But we said before the game that we have to make sure we're still involved at the end, and we are. The game's not over, there's a hell of a lot still to play for and now we're in a situation where Bury have got something to lose."
Alan Knill, the Bury manager, warned his side not to get carried away with the result - warning them that a trip to Wembley for the final is still not assured.
"It's going to be another really tough game at our place but I think we're ready for it," he said.
"For us to win in a play-off semi-final here is a fantastic achievement for us. Nobody expected us to win except us."