Mostly yes, unless you have bought one of the old ones. A couple of dozen buildings are listed. One conservation area carries the village's name. Nearly everything else was built after the war, with nothing special to protect. Your neighbours are already extending, and they keep the council busy with applications.
Historic England lists 28 buildings in the Stanwell area. One is Grade I, two are Grade II* and 25 are Grade II. Listing protects the whole building, inside and out. Almost any change that affects its character needs listed building consent from the council, on top of any planning permission, and that includes windows, doors and some internal walls. Twenty-eight buildings among several thousand homes is a small list. If the house you want is on it, though, the rules will shape everything you do to it.
There is one conservation area, named Stanwell. Inside its boundary, the council looks harder at changes that can be seen from the street. Some works that would need no application elsewhere need permission here, and demolition is more tightly controlled. Use Spelthorne Borough Council's planning map to check whether the address falls inside the boundary and whether the building is listed. The boundary can run between two houses on the same road.
One scheduled monument falls within the area. That is the strictest level of protection in England, and it mostly matters to homes on land right next to the monument.
The planning register shows plenty of activity. It holds 522 applications across Stanwell's area between April 2024 and June 2026, and 225 of them were made in the last twelve months. Most will be the everyday kind: rear extensions, loft conversions, porches and changes to commercial units. People in Stanwell change their homes, and Spelthorne's planning officers will already know the local semis well.
For an ordinary post-war semi or terrace outside the conservation area, modest rear extensions and many loft conversions can often go ahead under permitted development rights, without a full planning application. The limits on size and height are set nationally and can be removed for particular homes or estates by earlier planning conditions. A certificate of lawful development from the council confirms your plans fit within those rights, and it costs far less than finding out at sale time that they did not. Flats work differently. Changes to a flat usually need planning permission, as well as the freeholder's consent under the lease.
Freedom to extend in Stanwell is average overall. It is easy on the post-war streets that make up most of the place, and much more constrained in the small historic core, where the rules decide what you can do.