Yes, in most of Colnbrook, with a stricter set of rules around the old village. Thirty buildings are listed. One conservation area covers the historic core. Most homes are much newer than the high street. The planning register is busy enough to show neighbours extending all the time.
Colnbrook and its immediate surroundings hold 30 listed buildings: none at grade I, two at grade II* and 28 at grade II. Listing protects the whole building, inside and out, so almost any change to a listed home needs listed building consent from Slough council on top of planning permission, and work done without it is a criminal matter. Plenty of history, and none of it at cathedral level, but grade II is still a legal designation.
There is one conservation area, Colnbrook itself, covering the old village along what was the London to Bath road. Inside it, the council looks harder at extensions, windows, roofs, materials and demolition, and some work that would be routine elsewhere needs an application. The old high street is where the council pays most attention. On a late-twentieth-century close a new porch is mostly a matter of choosing bricks; inside the conservation area it starts with a form.
The council's planning records for the area log 1,420 applications between April 2024 and June 2026, 649 of them in the most recent twelve months. Those are submissions, and the count says nothing about how many were approved. It does show that people around Colnbrook are altering houses constantly, and the council's desk is rarely short of drawings.
For most buyers that means ordinary freedom. About a tenth of homes were built before 1930, and outside the conservation area a house that is neither listed nor a flat usually keeps its permitted development rights, so modest rear extensions and loft conversions may need only the right notifications. Flats are different, and about a third of Colnbrook's homes are flats, so their external changes need permission. Look up the address on Slough council's planning map to see whether it falls inside the conservation area boundary or is listed, and read the planning history for the house and the ones either side.
Your freedom to extend in Colnbrook is middling: straightforward on the newer streets, slower and more closely examined in the old village.