Yes, in most of the village, provided you don't buy the bit everyone photographs. The historic core is a conservation area. A few dozen buildings are listed. The post-war streets are fair game. Overton's planning rules bite hard in the middle and barely at all at the edges.
Historic England lists 45 buildings in the area. None is Grade I, 3 are Grade II* and 42 are Grade II. Listing covers the whole building, inside and out, so almost any change that affects its character needs listed building consent on top of any planning permission, and that includes things most owners would call maintenance. Buying a listed cottage means inheriting a relationship with a conservation officer that lasts longer than most marriages.
There is one conservation area, covering Overton itself. Inside it, the council takes a closer interest in anything visible from the street, from extensions and roof alterations to demolition and some tree work, and the freedoms a homeowner would enjoy elsewhere are narrower. The postcard street is postcard-shaped for a reason, and that reason now has a say in your dormer.
The neighbours have not been deterred. The planning register recorded 593 applications in the area between April 2024 and June 2026, with 261 of them in the last twelve months. That is a village where people are building, altering and extending all the time. Whether the committee said yes to all of them is another matter, and the register does not carry the answer consistently enough to say.
In practice, the answer splits by address. Outside the conservation area, and away from listed buildings, an ordinary house can often use permitted development rights for modest extensions and loft work without a full planning application, subject to the usual limits. A small sliver of the area falls inside the North Wessex Downs Area of Outstanding Natural Beauty, where those rights are tighter. Inside the conservation area or in a listed building, assume you will need consent and budget the time for it. Check the council's planning map for the exact address before falling in love with a kitchen that does not exist yet.
Overton sits in the middle on building freedom: easy enough in the newer streets, slow and paperwork-heavy in the old centre. Buy the character and you buy the committee.