Fence construction advice

I've just submitted a planning application for an 8ft fence on one side of the perimeter of our garden and a 6ft fence on the other.

The 8ft fence section abuts a reasonably well used pavement along a main road. Our garden is raised up 3ft above the pavement level so the extra height is required for privacy in the garden.

I'm just about to start getting quotes for building the fence, which is pretty long. The 8ft section will be about 35m long and the 6ft section about 20m long with a gate.

I'm currently thinking of requesting concrete bases to set into the ground with wooden posts bolted to them. The fence itself would be a feather edge fence.

This fence needs to be fairly heavy duty as we also have horse chestnut trees in the garden so kids try to jump over the fence (which is dead easy at the moment because the fence is only 3ft high).

Main questions are what spacing should be fence posts be and how many arris rails should be used to a 8ft high fence. I'm assuming we'd need 4.

Are there any cheaper alternatives to what i'm trying to achieve?

You could dig up the perimeter and pour a concrete trough.

I recently built a large perimeter fence and did the following...

1. dug post holes 600mm down.
2. used a 2400mm 100 x 100 post and used post-crete (3 bags per post).
3. This left 1800mm in height (6ft) and had posts 1.5 - 2.5m apart (i had to dodge tree stumps)
4. Put a brace along the top, middle and bottom.
5. Put 100 x 19mm boards vertically with 19mm spacing in between.

The spacing allows the wind to go through which is important if you have a tall fence.

I personally wouldn't use surface bolted post holders, I'd pre-treat and bury the timber so it has some length under ground level for strength and stability.

I'd wait to see if you get planning before worrying any further. Tall fences that are highway adjacent can be tricky to get approval for.