A couple of thoughts —
- Ivy, branmble are acid-loving type plants >> fight them off by making soil more alkaline — you didn’t indicate your location... does your area tent have more acid or more alkaline soil?
- you don’t really want to grow things against a fence anyway — particularly heavily needy plants like espaliers and grape. Grape I believe prefers alkaline/lime soil. Fruit espaliers would depend on what, but it’s imperative not to mix-plant fruit trees and vines that have different care needs or can host diseases or pests that affect a companion plant
- you could have a heavily mulched ornamental fenceline bed along the fence to neighbor to smother/weaken the bramble from emerging on your side as the first line of defense
- since you need a path of some kind along your espalier and/or grape, what about alkaline heavy path like concrete pavers or crushed sidewalk?
Kind of like this — how were you envisioning the espalier-grape border? I couldn’t figure it out. I tried putting an access walkway Between the espalier and grape.... On 2nd thought .. maybe grape next to the paver path, THEN the espalier ... but it would depend on sun direction, height of planting (grape trellis/arbor and height/type of espalier, etc.
Learning never ends because we can share what we've learned. And in sharing our collective experiences, we gain deeper understanding of what we learned.