Porch: Is project managing worth the effort for the saving?

[GettingOnWithItAll]

I want to have a porch built. Is the saving of project managing over a paying a builder likely to be significant?

See the image.

Some specifics:
@ I have the time and love to do things myself.
@ 1930s semi just south of London.
@ The previous owner agreed with the neighbour to build a porch together then withdrew.
@ The neighbour's outer wall straddles the boundary.
@ The neighbour is happy for us to build as was originally intended. I'm aware of the possible complications here.
@ I'm looking to have the rear door and another external door replaced so there may be some saving by having them done at the same time as the porch door & window.

 

[Ian H]

Do you need to project manage such a small project?

I’d decide what you want to do yourself and get a builder to do the rest.

I’m building one, and decided i’d do the foundations, get a bricky in to build it, then i’d buy and fit the windows and roof.