if you've never worn a sari before, could you not try a salwar kameez (tunic & bottoms) or lengha/chania choli (full length skirt/top) instead? way more comfy than sari (particularly if you're not used to one), but still traditional enough. nothing worse than wearing something you don't feel 100% comfortable and confident in!
Also, as someone else said, I don't know how traditional/religious the wedding ceremony is, but the original sari you linked to has black detailing, and some traditionalists believe it's an inauspicious colour to wear. Best to double check first.