You can make certain types of minor changes to your house without needing to apply for planning permission. These are called "permitted development rights" and are described in this guide. They derive from a general planning permission granted not by the local authority but by Parliament. Bear in mind that the permitted development rights which apply to many common projects for houses do not apply to flats, maisonettes or other buildings.
In some areas of the country, known generally as 'designated areas', permitted development rights are more restricted. If you live in a Conservation Area, a National Park, an Area of Outstanding Natural Beauty or the Norfolk or Suffolk Broads, you will need to apply for planning permission for certain types of work which do not need an application in other areas.
There are also different requirements if the property is a listed building.
The POS general advice is that you should contact your local planning authority and discuss your proposal before any work begins. They will be able to inform you of any reason why the development may not be permitted and if you need to apply for planning permission for all or part of the work.
You should also note that the local planning authority may have removed some of your permitted development rights by issuing an Article 4 direction. This will mean that you have to submit a planning application for work which normally does not need one.
Article 4 directions are made when the character of an area of acknowledged importance would be threatened. They are most common in conservation areas. You will probably know if your property is affected by such a direction, but you can check with the local planning authority if you are not sure.