VS can only see ANA 330 (331?) days out, whereas ANA's own program (and some other *A) can do 355. I'm not sure how tightly contested F seats are for LHR-HND, but you may have difficulty finding 2+ F on the same flight by T-330. I know I did for SFO-NRT.

The previous poster is right. Book at T-330 with some other segment and eat the $50 change fee.