You do not need to get building regulation approval yourself for alteration and installation work if you use someone registered with a 'competent person scheme'.
We recommend you use a tradesperson registered with an approved scheme so they can self-certify that their work complies with building regulations and will tell us directly about any work they have done on your behalf.
Exemption of Minor Works
Some minor building work (for example, small sheds, and most porches and conservatories) is exempt from the need to get approval. For some other types of work, such as replacement windows, electrical work and gas installations, you don't need approval provided that the work is carried out by a 'competent person'- for example, FENSA window companies and GasSafe heating contractors.