Yes, and heritage rules will rarely be what stops you. Ashford has a handful of listed buildings. There is one conservation area nearby. Its residents lodge planning applications by the hundred every year. History has left this town very little paperwork, and the neighbours are using the space.
Historic England lists eight buildings in and around Ashford, and all eight are Grade II, with no Grade I or Grade II* buildings at all. Listing protects the whole building, inside and out, so even a new window or an internal wall needs listed building consent from the council. With eight in the whole area, the odds of buying one by accident are slim. A town that appears in the Domesday Book as Exeforde has left eight listed buildings and a great many semis.
The mapping picks up one conservation area in the surrounding area, Bedfont Green. Inside a conservation area, changes that are normally automatic, such as some extensions, roof alterations and cladding, can need planning permission, and demolition needs consent. Outside it, which covers almost all of Ashford, the ordinary national rules apply.
There is also one scheduled monument in the wider area. That is the strictest tier of heritage protection, and it matters only to land on or right next to it.
Ashford's residents are clearly extending. Spelthorne Borough Council received 1,318 planning applications from the area between April 2024 and June 2026, and 516 of them came in the last twelve months. Those numbers cover everything from rear extensions to changes of use, but they show a town where altering a house is routine business. The semi is the commonest house in Ashford, and a semi is built with one blank side wall waiting for a two-storey extension.
For most houses, a modest single-storey rear extension, many loft conversions and an outbuilding in the garden fall under permitted development, which means no planning application at all, within national size limits. Larger or two-storey extensions need full planning permission from Spelthorne Borough Council. Flats have no permitted development rights, so any change outside the walls of a flat needs permission, and the freeholder's consent as well. Newer estates sometimes have permitted development rights removed by a planning condition, so ask the seller's solicitor for the property's planning history and check the original consent for any such condition. A house in a flood zone may also need a flood risk assessment for a larger extension, which is an Environment Agency matter, not a heritage one.
Freedom to extend is one of Ashford's real strengths. The rules that apply here are the national ones, the heritage restrictions affect a tiny number of homes, and the main limits on a bigger kitchen are the budget and the neighbour's patience.