Thank you, lvrugger.
I had made 4 batches using 8 grapes, 1 lime and 1 life, so that accounted for 32 bottles. Anyway, after another 12 baches, all french grapes, I got it. It certainly took more than 400 french grapes to achieve, even allowing for the few wild grapes which probably got in there ffom when I explored the tomb which leads to the little island.
I guess I paniced too soon. Thank you for your reasurance. Now I can get on exploring the possibilities of lifefruit/fruity mixtures. I understand that lifefruit makes the best nectar.