What are your goals?

Porch is a simplest type of extension, a small one-level room usually added at the existing door at the front or back of the property. A sunroom is similar to a conservatory, but with a solid rather than a glass roof, so more suitable for all year road use while still taking advantage of the natural light.

Usually a one-storey construction at the rear of the property, most frequently used to enlarge an existing kitchen, or to create an open-plan kitchen-living area.

The most substantial type of extension, which will significantly increase the living area of the house, and boost the property value.

Combines a side-return and rear extension to dramatically boost your living space.

This type of extension is very popular with owners of Victorian terrace properties -- in many of these the shape of the house allows for extending into the alleyway on the side of the house. This is an excellent way to increase usable space at relatively low cost and not to reduce your usable garden area -- often at premium in London.

This involves building on top of an existing structure, frequently a garage. New foundation and stronger walls may be needed to ensure structural strength, but there is a potential to create a substantial en-suite bedroom or even a separate studio flat, depending on the size of the existing structure.

Not strictly speaking an extension as such, but in case of properties with larger garden, often a good way to create extra space and relieve the pressure on the main house.