Listed building consent
Permission to make any changes, which is know as Listed Building Consent (LBC) is granted by your local councils conservation officer. He will decide if any alterations you wish to make are acceptable. Clearly if you are planning to purchase a listed building with the intention of adding an extension or plan to undertake extensive alterations for example, it would be sensible to have a conversation with this officer in advance.
Information & Advice 
VAT Information 
Log Book 
Specialist Insurance
Heritage Magazine 
Listed Building Plaques