Yes, in most of Whyteleafe you can extend a house without heritage rules getting in the way. The village has only a handful of listed buildings. One conservation area reaches into the surrounding area. The neighbours apply for planning permission all the time. The rule more likely to stop you is the one about flats.
Whyteleafe has five listed buildings, all Grade II. None is Grade I or Grade II*. Listing covers the whole building, inside and out, so changing a listed home means listed building consent on top of any planning permission. That rules out replacing windows or knocking through walls without asking first. With only five, the chances that the house you are looking at is one of them are low, but it takes a minute to check the national list.
There is one conservation area in the surrounding area: Kenley. Inside a conservation area, the council can look more closely at changes to the outside of a home, and some work that would go ahead elsewhere without an application needs planning permission. Demolition and work to trees are controlled too. Whether a particular house falls inside the boundary is on the council's map, and every house on the valley floor outside it is subject only to the ordinary rules.
There is also one scheduled monument in the area, the strictest level of heritage protection. It only matters for land on or right next to it. The nearby list includes the Second World War fighter pens on the former airfield at Royal Air Force Kenley, which are unlikely to come up in a kitchen extension.
The neighbours are not deterred. The planning records show 878 applications between April 2024 and June 2026, 393 of them in the last twelve months. The council's valuation list counts 2,390 dwellings in the area. People here put in planning applications as a matter of routine, and every application is on the public register, so you can read what the houses on either side of yours have already asked for.
What you can do depends on what you own. A house outside the conservation area and not listed usually has permitted development rights, which allow modest rear extensions, loft conversions and outbuildings within national size limits without a full application. A flat has no such rights for most alterations, and a leaseholder also needs the freeholder's consent under the lease. Flats make up most of Whyteleafe's homes, so for many buyers the first question about an extension is who owns the roof. Ask the council whether any permitted development rights have been removed on the street, and read the lease if the home is a flat.
Whyteleafe gives homeowners plenty of room to extend. Heritage protection hardly applies, and the real limits come from the type of home you buy.