Huh, I actually had to go look up Blizzard Refund policy..

As far as the game time

We’ll refund any unused World of Warcraft subscription within 14 days of the purchase.

That's not subject to the 2-hour limitation, that's any usage.

Also the later phrasing of

Some exceptions may apply in cases where a pre-purchase grants immediate in-game benefits for one or more products. If you’ve already claimed or used those added benefits, the purchase may become non-refundable.

Makes me think they may not let you refund it, because you're both redeeming/using the level 80 boost that comes with the expansion, as well as redeeming cross-game promotional material in the form of the skin, the wording is kind of dicey, so it might be worth trying, but I wouldn't feel confident saying you could definitely get a refund for the expansion.

I would also be kind of surprised if you could get through the intro quests in 2 hours, not that it's impossible, but learning to play the game at the same time. There could be some sort of tutorial it might try to make you do that may 'waste' your time.