Lean to pergola

[Amatu]

Hi,
Maybe someone will be able to help me with this.
I am planning to build a wooden pergola at the back of the garden of a terraced house. I want it to be the width of the garden, i.e. it leaves no space ( or just 20-30 cm) between the pergola and the fence. I'm afraid I won't be able to place the carbonized sheet on the right side of the roof if I start from the left. I don't want to go into my neighbours garden to finish the roof. Any tips on how to do it?