I would like to extend my house. My project provides for the new construction to be built on the boundary with my neighbour’s property. Do I have the right to do this?

It depends. The law does not expressly prohibit it. However, it refers to local planning rules (contained in the local urban plan, or PLU). You should therefore contact the town hall of the municipality where your house is located (Art. L.151-17 of the French Town Planning Code).