Usually yes, but read the deeds as closely as the planning rules. Most homes aren't listed. Three conservation areas cover the Horsleys and Effingham. The neighbours apply for planning permission constantly. Some titles still carry covenants from the old Lovelace estate. The planning office is only one of the people with a say.
The wider area holds 76 listed buildings: 2 at Grade I, 2 at Grade II* and 72 at Grade II. Listing protects the whole building, inside and out, so almost any alteration to one needs listed building consent on top of any planning permission, and the works have to respect what made it worth listing. Grade I and II* are the top tiers and the hardest to change. Grade II is the everyday end, and still a long way from a free hand. With 76 in a village of mostly post-war detached houses, the odds are that the house on your shortlist isn't one of them. Check the listing anyway, because it's the owner who carries the liability, not the estate agent.
There are 3 conservation areas in and around the village: East Horsley, West Horsley and Effingham. Inside them, the council looks harder at anything visible from the street, including extensions, demolitions, roof changes and work to trees, and some changes that would go through without permission elsewhere need consent here. Planning is decided by Guildford Borough Council, with advice from the local Horsley council, so an application gets looked at by people who live nearby.
There is 1 scheduled monument in the wider area, the strictest tier of heritage protection. It only matters if your land sits right up against it.
The planning records show the village isn't shy about building work. The area logged 2,467 applications between April 2024 and July 2026, and 1,076 in the last twelve months of that period. That's a lot of people wanting bigger kitchens, and it tells you that altering a home here is a normal thing to do rather than a fight.
The ground needs more thought than the paperwork. The British Geological Survey puts the whole area in class 3 for shrink-swell clay, the kind of ground that swells when wet and shrinks when dry. That's a published hazard class, not a reason to panic. It does mean foundations for an extension may need to go deeper than a builder's default, especially near trees. Get a structural engineer's view before the architect's drawings are final, not after the footings are dug.
One listed building in the area is on Historic England's Heritage at Risk register. That describes a historic building in poor repair, which may qualify for grant support and will get close scrutiny from anyone approving work on it. It's a matter for that building's owner, not a hazard to the buyer of an ordinary house down the road.
In practice, an unlisted house outside the conservation areas starts with the usual permitted development rights, while a house inside one, or a listed one, should assume a planning application for most visible changes. Two further checks catch East Horsley buyers out. In the early 1900s the 3rd Earl of Lovelace sold his fields with restrictive covenants attached, so a solicitor should read the title for anything that limits building before the planning question even starts. And a quick call to the planning office before exchange costs far less than finding out later that the garden room needs consent.
Freedom to extend here is middling. Most houses can grow with the right paperwork, but between the conservation areas, the listed stock, the old covenants and the clay underneath, very little here gets built on a whim.