Permaculture and companion planting in coastal garden

My new garden is 1 mile from the coast, faces south west, the top is as high as the 2-storey house with a flat little veg plot at the top. The rest is strips with bought-in well-draining soil, held with dry-stone walling.  I want to grow veg, flowers, climbers, shrubs in the strips, there's an ugly 3-section trellis in the most sheltered spot & a small frost pocket next to the house but the climate in Ceredigion is heaven compared with our previous garden in Powys hills! It's a hot garden but south east winter winds can be fierce - needs more protection. Ideas please including what to grow in and up these georgous walls.