Yes. Very little in South Woodham Ferrers is protected, so extending a house here mostly comes down to the ordinary planning rules and your budget. Only three buildings in the town are listed. None of them is in the top two grades. There is no conservation area. The main thing an extension has to contend with is the clay underneath it.
Historic England lists 3 buildings in the town, all at Grade II, with none at Grade I or Grade II*. Listing means any alteration to a listed building, inside or out, needs listed building consent on top of planning permission. In a town of several thousand homes, that affects only a handful of owners. There is also no conservation area and no scheduled monument within the town, so the extra controls that come with those don't apply anywhere here. The town was mostly farmland until the railway arrived in 1889, so very little here predates the trains.
The neighbours are already extending. From April 2024 to June 2026, 2,678 planning applications were made in the area, 1,200 of them in the last twelve months. In a town planned by Essex County Council in 1974, with most of its homes built in the following decades, a lot of owners are adding the extra bedroom or bigger kitchen the original plans left out.
The ground needs more thought than the paperwork. The British Geological Survey rates the area for shrink-swell, the way clay swells when wet and shrinks as it dries, and its highest class here is Class 3, which covers 100% of the area. On clay like this, an extension usually needs deeper foundations than it would on firmer ground, and the depth depends on the soil and on any nearby trees, whose roots dry the clay out. Get a structural engineer to look at the ground and the foundations before the architect draws anything. The fields the town was built on are still underneath it, and the clay doesn't care what the planning rules say.
In practice, many single-storey rear extensions, loft conversions and outbuildings can go ahead under permitted development, the national rules that let you build within set limits without a planning application. Larger or more prominent projects need full planning permission from Chelmsford City Council. On newer estates, the original planning permission sometimes carries conditions that remove permitted development rights. Ask the council for the permission covering the house you're buying, and read its conditions, before you assume a rear extension needs no application.
Very few places make extending as easy as South Woodham Ferrers does. Heritage protection is almost absent, and the main extra cost of extending here is the foundations the clay requires.