There are a number of lists and databases for accredited heating
installers which include the installation of wood fuel systems:
You may also want to consider approaching an energy services company
(ESCo).
Installer accreditation
HETAS
HETAS are the official body recognised by Government to approve
biomass and solid fuel domestic heating appliances, including the
registration of competent installers.
HETAS installer registration
information
Microgeneration Certification Scheme (MCS)
The MCS is an independent scheme that certifies microgeneration
installers and products against robust criteria providing greater
protection for consumers.
MCS installer
certification information