Yes, and for most of Netley history doesn't get a say. There are only a handful of listed buildings. The one conservation area surrounds the abbey. The clay underneath the whole village gets more of a say than the planners do. For most homes the paperwork is the easy part and the foundations are the hard part.
There are 14 listed buildings in and around Netley: none at Grade I, 2 at Grade II* and 12 at Grade II. Listing covers the whole building, inside and out, so any change that affects its character needs listed building consent on top of any planning permission, and work done without it is a criminal matter rather than an administrative one. With 14 in the area, the chance that the house you are looking at is one of them is small, but it is worth checking on the listing register before assuming otherwise.
There is one conservation area, Netley Abbey. Inside it, changes that would pass without comment elsewhere can need consent, particularly anything visible from the street, and demolition and work to trees come under closer control. Outside it, the rules are the standard national ones.
There are also 4 scheduled monuments nearby, the strictest tier of heritage protection. They matter mainly to anyone with land next to one, where even digging for a foundation can become a question for the heritage authorities.
The neighbours clearly aren't put off. The planning register holds 1,333 applications from April 2024 to July 2026, 493 of them in the last twelve months. That is the most useful evidence here: people in and around Netley alter, extend and rebuild their homes routinely, and the application process is a normal part of doing so rather than something to be afraid of.
The ground is the real constraint. The British Geological Survey's published shrink-swell hazard reaches Class 3 here, and 100% of the area is at that class or above. Shrink-swell means clay that expands when wet and shrinks when dry, which moves shallow foundations over the years. For an extension, that means deeper foundations than the builder's first quote may assume, and an early look from a structural engineer, particularly near large trees. It is a design issue, not a reason to walk away.
In practice, a house outside the conservation area and not on the listing register is likely to have the normal permitted development rights, which cover many rear extensions and loft conversions without a full planning application, subject to the national size limits and to the council's prior-approval process. Inside the conservation area, or on a listed building, assume consent is needed and ask the council before paying an architect to draw anything. Either way, checking the property's own planning history for removed permitted development rights costs nothing and can save an argument.
Freedom to extend is middling: easy for most of the village, restricted around the abbey and the listed buildings. The planners are the smaller hurdle, and the clay under the foundations deserves more attention.