Just trying some permie beds under existing overgrown hedge/ trees with evergreen canopy have cut down most but some remain
am not certain to cut more or just believe that the grapevines veg and frut trees am growing underneath - having built up the soil with a layer of manure a layer of wood chip and a layer of clay followed by a layer of compost and will finish with a layer of woodbark
Want to plant under the trees and allow the new fruit to grow before cutting down the leylandii/tuja / holly / laurel
Should I just put my big person pants on and start cutting or is there some clever way that veggies find water from tree roots please
There are lots of variables, so it's hard to say for sure. In general vegetables grow great under trees, barring excessive shade, etc. I've seen examples where vegetables grow better under trees than out in the open, but this is in established no-till systems. Sounds like you've added lots of organic matter, so there shouldn't be a problem with the soil holding onto moisture. The only question then it's if you get enough rainfall to support the number of plants you're growing. When in doubt, planting things further apart reduces water stress. Steve Solomon's Gardening When It Counts has some great information on growing vegetables without irrigation.
In my experience nothing will grow well near a large evergreen hedge, they suck all the water and nutrients out of the soil and annual veg will have no chance competing. whether you will need to water often depends on your climate, but even here where it rains all summer plants near large trees need watering.