Green Grapes ......... when to cut back leaves an how much

[redzzed]

Oxfordshire Uk , we have several healthy green grape vines , mosty west facing and they are very bushy .

I have cut back the leaf growth to expose the grapes themselves (which look good but look 2 weeks or so from harvesting) .

But how much do they need to be cut back ??
Does the fruit rely upon the leaves to catch the sun and nourish them , or does
the fruit need only direct sunshine ??

[Skipley]

Strip the leaves for direct expose.