I'd just gotten to the point that I only took my prenatal and B50 complex (my LP is crap without it) during the TWW. Stopped taking the DHA supplement though as it was more expensive and I didn't see the point (and I bought some nasty chewable ones that were on sale and couldn't stand them).
This cycle, not only did I drink wine at about 7dpo (and I NEVER drink!), but I only took the B complex for most of my TWW because I went out of town and forgot my vitamins. So I just bought another bottle of B complex and waited until I got home to start up the prenatals again. After my BFP I've started with the DHA again too... hopefully I'll get through this last box of chewables soon.
Like mjemma said, plenty of people don't take vitamins before they get pregnant and everything is fine. Even if you give AF week off of taking them, sometimes a short break can be refreshing!