Why is it wrong to dig foundations in your garden before the planning comes through. It's only like digging a hole in your garden. If the neighbours are on side and happy I don't think there's any moral quandary. Crack on if you're brave and confident the planning coming, if thats what you want to do.
Half the plumbers i know wouldn't have a clue about how wc works and curves. One i know refers to wc as basically you tell the boiler what you want it to do and it just ignores you and does what it wants 🤣