For the neighbour consultation? After.
I'll send plans to the council assuming that there will either be a way to partially build over the chamber, or that it will be moved, i.e. plans for an extension which would be fine if there were no drains anywhere near.
If I subsequently need to make the building smaller than approved for any drain- or cost-related reasons that won't be an issue.
Once I know that I would be allowed to build it I'll start down the route of getting designs and paying for a man with a camera on a stick.
