Permitted development
If you wish to have a formal decision from the council stating that you don't need planning permission or if you know the work you want carry out or existing work/use is permitted development, doesn't require planning permission, then you should apply for a Certificate of Lawfulness on the Planning Portal
Change of use from offices to residential
In May 2013 the entire Borough was made exempt from the liberalisation of the permitted development rights which removed the need for planning permission for changes of use from offices to residential.