We’ve already received some reports and this seems to be affecting a few realms, please hang on tight while our gnome and goblin engineers attempt to fix this.
We’re really sorry for the inconvenience and we’ll try to be as brief as possible.
You’ll be able to get more frequent and better updates on the status of this issue in this thread over on our support forums:http://eu.battle.net/wow/en/forum/topic/8048295906?page=20#394
and on their twitter:@BlizzardCSEU_EN
On another note, if you really don’t want to take any break from WoW, and since this is only affecting a few realms, feel free to login to another realm and create that new class that you’ve always thought about trying but never actually got around to it.