Conservatories fall under the same planning regulations as any extension or addition to a house.
In many cases, adding a conservatory to a house is permitted development (PD), not requiring an application for planning permission, provided all of the limits and conditions of PD are met.
Whereas we can advise, only the planning department can say for certain that a proposal is PD. When in doubt, we recommend applying for a certificate of lawful proposed development (CoLU) to confirm.