Easiest thing to do is contact the council planning department and ask to speak to their conservation officer or if the don't have one the planning officer for your area will probably be able to help.
Planning departments are actually very helpful and sympathetic if you approach them. They are not sympathetic if you do things they haven't approved.
Good advice, unless you live in Spain, where the opposite is true. Do it and hope nobody notices is the rule here. Contacting planning officers yourself is just asking for a barrel load of trouble and petty interfering.