Block paving specialists

[Sunny Intervals]

altho the aco drains wont be "plumbed in" for that cash.

So you will be getting a trough closed at both ends which will collect leaf and any other run off muck, they do that even when plumbed in  :rollin :rollin
I would make sure they are closed at the end that borders you neighbours property, and fall onto yours.
Depending on the channel depth you are using that could be a lot of water about to create a soft spot somewhere.
You already mention your neighbours drive is dropping a bit where he drives on,