If your building is Listed (either on the national List maintained by Historic England or the Local List maintained by Reading Council) or if has an Article 4 Direction on it then your Permitted Development Rights have been removed to a degree. To undertake certain works you will have to apply for Listed Building Consent / Planning Permission for certain works.
You certainly need to find out more before just “getting on with your planned works”. To do so go to:
Is your building Listed? To find out go to HERE
Listed Buildings in Reading go to HERE
Planning Consent requirements go HERE
Reading Council’s list of Locally important Heritage Assets HERE
Buildings with Article 4 Directions which remove PDRs. HERE