Anything that forms a permanent part of the property is deemed to be a fixture and is therefore included in the sale. This includes
The seller may not remove them when he leaves, unless it is clearly stipulated in the Sale Agreement that he will do so.
Light fittings are considered fixtures, but a seller may wish to take a chandelier that he bought for the house. However, he needs to specify this in the Sale Agreement, excluding it from the sale, and he ought to replace it with another light fitting, though this can be negotiated.