Extending or altering a home in Peacehaven is easier than in most of coastal Sussex, because the heritage protection sits mostly in two villages that the town itself does not overlap with. There are 18 listed buildings in the wider area. Two conservation areas cover the villages of Telscombe Village and Piddinghoe. One scheduled monument sits nearby. For most of the town, the planning path is planning-portal ordinary rather than heritage-bureaucratic.
On listed buildings, the count sits at 18 in the wider search area. One of those is Grade One, the rest are Grade Two, and none are Grade Two-Star. Owning a listed property means every external and often internal alteration needs listed-building consent, which is a slower and more scrutinised process than ordinary planning permission, and it locks you into a relationship with the local conservation officer whether you wanted one or not. Losing a chimney, changing a window, adjusting a stair, or knocking through a wall can all trigger the requirement. That constrains what you can do to the fabric and can add months to a project. What matters for Peacehaven is that the number is small, and the listed stock is concentrated in the historic pockets rather than scattered through the streets where most of the housing sits.
On conservation areas, there are two in the wider area, at Telscombe Village and Piddinghoe. Central Peacehaven does not sit inside either boundary, so most of the town's housing sits outside the extra-consent regime. Where a conservation area does apply, minor changes that would be permitted development elsewhere can require extra consents, and the local authority can be stricter about materials, roof lines, boundary treatments, and anything visible from a public view. The practical rule is to check whether the specific address is inside a designated boundary before assuming what you can do.
For a typical Peacehaven house, which is a post-war semi, terrace, bungalow or detached built between the fifties and the early eighties on the town's grid, the freedom to extend is on the generous side. Standard permitted-development rights apply in most cases, meaning single-storey rear extensions, loft conversions with rear dormers, and side infills can often be done without full planning permission, subject to size and boundary conditions. Anything larger, in a more sensitive location, or in a more protected pocket will need a submitted application. For most of Peacehaven, the extension debate is a conversation with your neighbour about light, not one with a conservation officer about roofing slates.
Overall, Peacehaven scores three out of five on freedom to extend or alter. That is a middle band on the scale, sitting between the easiest new-build estates and the near-frozen conservation areas of the wider county, and it reflects the mix of an unprotected core and a protected village fringe.