Normally, maximum height is 2m
Post, arris rails and feather edge is a good fence.
Builders, fencers, hard landscapers can do fencing.

Within 3 metres of a road edge fences should not be more than 1 metre in height.
Otherwise anything up to 6,6 feet is normally acceptable, any higher requires planning permission, but its weather any body reports you. in my erea all housing is meant to have open plan front gardens but every body has planted shrubs and put fencing up.

ive only ever come across 9ft concreat fence posts so if ur going higher than 6'6 would be tempted to get some tanalised fence posts.

hope this helps a bit

2m backyards
1m frontyard and or near highway

you are aloud to have the fence including the wall no more than 1mtr950mm tall prob the same as ur neighbours in hight and it shouldnt matter if their is a road / footpath because the wall is already their , and best materials wld be long enough to be in the ground abit as well as using (m10 ram bolts) to fix it to the wall or (studing and cemfix) with 8ft 4x4 posts (2ft in the grond,the 5ft wall ,and 1 and half foot on the wall, and cantrail fixed with 4"scews wld defanetly be ok, if it was one long level stretch of wall the best do the fence with 1.8 inters for strenght u wldnt nd gravel boards as its its siting direct on the wall