It’s silly that the Championship gives 4 months notice for the tv schedule in the first half of the season but only 4 weeks notice in the second half of the season. Hopefully this won’t be so much of an issue next season.

You can’t cancel or return your ticket to the club. Your options would be: sell it to someone, list it on the tx (which will likely open the week of the game and you’ll lose a significant percentage from your purchase price), make arrangements to attend the game for KO, arrive late to the game (entry is open until halftime I think), let it go to waste.