Yes, in most of Lyminge you can extend without a fight. Only a small number of buildings are listed. People put in planning applications all the time. The village sits inside protected countryside, so a few permitted development rights are narrower. The real snag is under the lawn, not in the planning office.
There are 15 listed buildings in the area: 1 at Grade I, 2 at Grade II* and 12 at Grade II. Listing means almost any change that affects a building's character, inside or out, needs listed building consent on top of any planning permission, and the rules follow the building rather than the owner. With 15 listed buildings in a village this size, the odds are firmly against yours being one of them. The estate agent will tell you if it is, usually in a font size that suggests it's a selling point.
The neighbours aren't shy about building. There were 438 planning applications between April 2024 and June 2026, and 187 of them came in the last twelve months. That's a steady stream of people adding rooms, converting lofts and rethinking kitchens. It tells you the process is well trodden here. It doesn't tell you how any single application will turn out.
The ground needs more thought than the planning. The British Geological Survey puts the area at class 3 for shrink-swell, and that class covers every postcode. Shrink-swell ground expands when wet and contracts in dry spells, which moves foundations that aren't built for it. In practice that means deeper foundations for an extension, particularly near trees, and getting a structural engineer to look at the soil before the architect gets carried away. Plenty of extensions get built on ground like this. The ones that go wrong tend to belong to owners who assumed chalk hills meant solid ground everywhere.
Most rear extensions, loft conversions and outbuildings on an ordinary unlisted house can go ahead under permitted development, within the national size limits. The whole of Lyminge sits in the Kent Downs Area of Outstanding Natural Beauty, where some of those rights are narrower, particularly for side extensions and changes to external materials, so a design that would pass without comment in a suburb may need a full application here. Before committing to a plan, ask the council whether it needs consent. The answer costs little, and a surprise refusal costs a lot more.
Extending a home in Lyminge is easier than in most places this pretty. Heritage rules rarely bite, so the main jobs are a good engineer for the clay and a design that respects the protected landscape.