Some threads on here too -
http://www.northstandchat.com/showthread.php?283697-Barcelona
http://www.northstandchat.com/showthread.php?258439-Buying-Barcelona-match-tickets
and a Barca forum too -
http://www.barcaforum.com/forumdisplay.php/18-Travel-section
Hope you get tickets, its an...
Champions League games are the best to go to as they locals aren't interested. We watched them v Spartak last September when there was "only" 80k in attendance. Tickets available on the official website or from official outlets all over the city.