There is no substitute for seeking professional advice. However, here is a small selection of the most useful heritage, planning and design resources available on the internet.
Historic England (formerly English Heritage) are the Government's statutory advisors on all matters relating to the historic environment. Their website is vast and includes a number of informative publications which are free to download. If you are planning a renovation project, the guide to Part L of the Building Regulations is particularly useful.
The National Heritage List for England is an online database which brings together information on all nationally designated heritage assets in one place for the first time.
The Planning Portal is the Government's online planning and building regulations website for England and Wales. It is a vast and useful website, including guidance on the types of permissions you may need.
SPAB have a very good website -
Like SPAB, their website is very good and includes guidance on maintaining and repairing historic buildings. It is targeted specifically at Victorian and Edwardian properties and includes good information on interiors.