You can extend most houses in Woburn Sands, though heritage rules aren't the main thing to plan for. Listed buildings are few. One conservation area covers the older core. The neighbours file planning applications constantly. The ground underneath every house is what should shape the design.
Historic England lists 13 buildings in and around Woburn Sands: none at Grade I, one at Grade II* and 12 at Grade II. Listing covers the whole building, inside and out, so almost any change to one of those 13, from a new window to moving an internal wall, needs listed building consent on top of any planning permission. For the thousands of other homes in the area, listing doesn't come into it. The odds of owning a listed house here are low, and the post-war semi next door is free to build its loft conversion.
There is one conservation area, named after the town, covering its older streets. Inside it, the council takes a closer interest in anything visible from the street, including demolition, front boundaries, materials and the shape of an extension, and some changes that would go through automatically elsewhere need an application. The boundary runs between ordinary streets, so look up the council's conservation area map for the house you want to buy. Two semis built at the same time can come under different rules depending on which side of the line they fall.
One scheduled monument falls within the area: Danesborough Camp, an Iron Age hill fort on Aspley Heath. Scheduling is the strictest form of protection, but it matters only to land on or next to the fort. Back gardens in the town are a long way from it.
The neighbours certainly aren't waiting for permission to want things. Planning records show 907 applications in the area between April 2024 and June 2026, 518 of them in the last twelve months. That is a town busy with side extensions, loft dormers and garden rooms. The applications don't show which were approved, but they do show that nobody here is deterred by the paperwork.
The ground matters more than the paperwork. The British Geological Survey puts the area in shrink-swell class 3, and the whole area reaches that class. Shrink-swell describes clay soils that expand when wet and shrink as they dry, moving anything built on them. For an extension, that means foundations dug deeper than the minimum and a structural engineer's assessment before a builder quotes, especially near trees whose roots draw moisture out of the soil. The town got its name from sand, and builders still have to plan for the clay.
In practice, a house outside the conservation area and off the listed register will usually have the standard permitted development rights for rear extensions and loft work, subject to the national size limits, and the council can confirm with a lawful development certificate. Inside the conservation area, assume the front and sides need an application. On one of the 13 listed buildings, assume nearly everything does.
Woburn Sands is middling for extending: most houses have room to grow under the normal rules, a handful are tightly controlled, and every one is built on ground that needs proper foundations.