And they nearly fell behind in the 27th minute when Cairney saw his curling free-kick beat the Reading wall only for the Omani stopper to claw it out before saving Sone Aluko's follow-up.
Royals have nearly sold out all 24,000 tickets for the mouthwatering semi-final second leg after the first leg at Craven Cottage ended 1-1 on Saturday.
Kermorgant was so close to scoring early in the game when he unleashed a strike from inside the area, but Fulham goalkeeper Marcus Bettinelli would make a fine save.
With Reading clinging on for the final 20 minutes, Al Habsi pulled off an even better stop to tip Kevin McDonald's drive over the crossbar.
"I was thinking if I score it might be enough to get us in the final, I was determined not to miss it". We knew it would be from the start.
"As a player it was great to get there and as a manager it will be fantastic". And after counting the votes, we have discovered you think that Kermorgant is the 27th best player in the Football League.
"This is the best English referee - an global referee - so I can not complain".
Jaap Stam's men came into the night having drawn the first leg away at Craven Cottage, so all was to play for. I've been there myself as well, you think about that result and do you take risks in going forward or do you drop in deep and defend that 1-0.
I disagree. McShane's absence for Reading is a blow and the potential absence of Jordan Obita a concern but I'm sure the last thing that Stam is going to do is send his side out in a gung-ho manner. If you concede a goal it can be a very hard game, but you need to trust in yourself as well and that's what we've done today in believing in how you can play and taking some risks as well.
There was evidence of tension in the opening stages of the game although it was Fulham that initially looked the stronger side with the movement of Sone Aluko in particular testing the home back-four.
Liverpool and Tottenham are both keen on the Fulham left-back but Cairney has interest from recently promoted Newcastle United.
The Cottagers have never scored more than one goal in a play-off match.
The team that finished sixth in the Championship has won promotion via the play-offs just once in the last 11 seasons - Blackpool in 2009/10.
It was nil- nil at half time, but shortly into the second half a penalty saw Yann Kermorgant score the only goal, to book the Royals place at Wembley.