Installing a wood-burning or multifuel stove is a major undertaking and there are only two routes to legally install an appliance into your home :
(1) Use a HETAS registered installer who is able to certify that the work complies with the relevant Building Regulations
(2) You apply to your local authority building control department for a building notice and pay the appropriate fee (typically up to £300)
It is generally much simpler and cheaper to use a HETAS registered installer who will leave you with a Certificate of Compliance as a record of the job and that it complies with Building Regulations. A copy of the certificate is forwarded to HETAS who notify the local authority on your behalf.
Failure to notify the work through the registration scheme (in this case HETAS) or directly to the local authority can lead to enforcement. It can also cause problems for future house sales if there is no official record of a compliant installation and may invalidate your insurance if you are the unfortunate victim of a fire.