For most houses in Bradley Stoke, extending is about as unencumbered as home alterations get in England. The whole area carries just five listed buildings. Every one of them sits at the lowest grade of protection. There are two conservation areas, both out on the older fringes rather than in the estate itself, and no scheduled monuments at all. If your home is one of the thousands of ordinary modern houses here, the heritage rulebook barely applies to you.
Take the listed buildings first, because they are the strictest control and the rarest. Five listed entries across the wider area is a small number, and all five are grade two, the tier that covers most of England's protected buildings and the most workable to actually live in. Listing is not a ban on change, but it does mean that altering anything of interest, inside or out, needs listed building consent on top of ordinary planning permission, and that consent looks hard at original features before it says yes. The saving grace in Bradley Stoke is the sheer unlikelihood that your house is one of the five. This is a town built in the main between the early eighties and the early two-thousands, so the odds of buying a listed home here are slim to begin with.
Conservation areas are the wider net, and there are two, at Lower Almondsbury and around Church Lane in Winterbourne. Both sit on the older edges of the area rather than across the modern housing. Inside a conservation area the controls tighten in ways that catch people out: some works that would be automatic elsewhere need consent, tree work comes under notice, and the range of what you can do without asking shrinks. The important thing is that these constraints are geographic. If your house falls inside one of the two boundaries, they bite. If it sits on the estate proper, they leave you alone.
In practice that produces a clean split. The typical Bradley Stoke house, modern and unlisted and outside any conservation area, keeps the full run of permitted development rights, which means a good deal of extending, converting and re-roofing can happen under those rights without a full planning application, subject to the usual size limits and to building regulations sign-off. The homes that need to tread carefully are the handful of older, protected ones and anything inside the two conservation boundaries. The single most useful thing you can do before buying is confirm which of those two categories a specific property falls into, because that one answer reshapes the entire job, the budget and the timeline.
So, can you extend a house in Bradley Stoke. For the vast majority of homes, yes, and with less friction than most places carry. A few listed buildings and two conservation areas keep the area's overall freedom at middling rather than wide open, but that constraint is concentrated on the edges, and the modern estate at the heart of the town is about as free a canvas as English planning tends to allow.