Usually yes, but expect paperwork. Most homes aren't listed. Two conservation areas cover parts of the village. The neighbours apply for planning permission all the time. You'll probably get your extension, but not without a planning officer having a say first.
The wider area around Windlesham contains 166 listed buildings. One is Grade I, six are Grade II* and 159 are Grade II. Listing covers the whole building, inside and out, so almost any change to its character needs listed building consent on top of planning permission, including internal walls, windows and fireplaces. Most of Windlesham's housing isn't listed. But if the house you're looking at is, you're buying a building the council regards as partly its responsibility, and it will want a say in any change you make.
There are 11 conservation areas across the same wider area, and two sit in the village itself: Windlesham, Church Road and Kennel Lane, and Windlesham, Updown Hill. A conservation area doesn't protect individual buildings. It protects the look of the streets. In practice, changes that would be routine elsewhere, such as work visible from the road, demolition and tree works, need more checks inside one. A house on the right street means asking permission before you do anything to the frontage.
The area also contains seven scheduled monuments, the strictest level of heritage protection. They mostly matter if your land sits right next to one, and for most homes in the village that won't be the case.
The planning register shows how often residents apply for changes. Between April 2024 and June 2026, 296 planning applications were submitted in the area, 150 of them in the last twelve months. That's steady activity from people wanting more space and working through the process to get it. Those figures show how many people applied. They don't show how many succeeded, so treat them as evidence of demand, not a success rate.
In practice, a detached house outside a conservation area and with no listing has the most freedom. Many rear extensions and loft conversions on a house like that fall under permitted development and need no full application, subject to the national size limits. Inside a conservation area, some of those rights are reduced, and on a listed building almost nothing counts as routine. Before you buy with an extension in mind, check three things for the exact address: whether it's listed, whether it's in a conservation area, and whether the council has removed any permitted development rights on the property. The council's planning pages and the planning history for the address will tell you most of what you need.
Freedom to extend is limited in Windlesham, because so many homes sit close to a listed building, a protected street or both. The extensions do get built, but most need permission first.