Yes, with very little heritage standing in the way. The whole place has one listed building. It has no conservation area. The neighbours file hundreds of planning applications a year. The limits here are the plot and the budget, and history barely comes into it.
Historic England lists one building in Ashford Common, and it is grade II. None are grade I or grade II*. Listing means almost any change to that building, inside or out, needs listed building consent from the council on top of any planning permission. The area has no conservation area and no scheduled monument either. With a single grade II entry, the chance of the house you are viewing being the one that needs consent is slim, and the conveyancing searches would flag it if it were.
Planning records for Ashford Common show 1,751 applications between April 2024 and June 2026, and 668 of them in the latest twelve months. Those are applications made, with no indication of how many were approved. In a place of about 9,400 people, 668 applications in a year shows that changing your house is a common pastime here.
Without a conservation area or a crowd of listed buildings, most houses here come under the ordinary national permitted development rules. Within those limits, single-storey rear extensions, many loft conversions and garden outbuildings can go ahead without a planning application. Anything bigger, or anything outside the limits, goes to Spelthorne council for planning permission in the normal way. Two things can still narrow the allowance on a particular house. A previous owner's extension may already have used some of it up. Or the original planning permission for the estate may have removed some rights. Check the house's planning history on Spelthorne's planning portal, and ask the council whether any direction removes permitted development rights on that street. Just over half the postcodes are in the Environment Agency's medium-risk river flood zone, so a full application there may also need a flood-risk report.
Freedom to extend is one of Ashford Common's real strengths. The rules that apply here are the ordinary national ones, so how far you can go mostly depends on the size of the plot and the budget.