In most of Laleham, yes, as long as you go through the usual planning process. The listed buildings are few and almost all Grade II. There's one conservation area, around the old village centre. Away from it, the post-war houses and bungalows face no more red tape than any other suburb. The stricter rules mostly apply around the church.
Laleham has 21 listed buildings. One is Grade I, none are Grade II* and 20 are Grade II. Listing covers the whole building, inside as well as out, so changing one needs listed building consent from Spelthorne Borough Council on top of any planning permission. With 21 in the village, you're unlikely to buy one by accident. Your survey and the conveyancing searches will flag it if you do.
The village centre has been a conservation area since 1970, and it's the only one in Laleham. Inside it, the rules on demolition, some extensions, cladding and trees are tighter, and the council looks harder at anything visible from the street. The area is clustered around the old centre. Outside it, the extra conservation-area rules don't apply.
There's also one scheduled monument, the strictest protection there is. Works to the monument itself need consent from the national government's heritage process, but it only affects land on or very close to it.
Plenty of people do get changes approved. In the area around Laleham, 1,756 planning applications were made between April 2024 and June 2026, including 740 in the last twelve months. Anyone extending here will have neighbours who also read the planning list.
Away from the conservation area and the listed buildings, ordinary houses usually come with permitted development rights. Those allow some rear extensions, loft conversions and outbuildings without a full planning application, within national limits on size and position. Flats don't have those rights. Inside the conservation area, some of them are reduced. Ask your solicitor to check whether an earlier planning permission on the house removed its permitted development rights. On older estates the council sometimes did that, and the first owner to find out is usually the one with an extension already drawn up. Laleham also has a lot of floodplain, so any extension in the higher-risk flood zones will need to deal with flood risk as part of the planning application.
Laleham is middling for freedom to extend. You have real freedom on most streets, but around the church and on any lower ground near the river, expect a longer list of questions from the council.