You can apply to 'regularise' building work. This is for unauthorised work (work done without building regulations consent) that was done after 11 November 1985. The owner of the property will need to ensure that they have enough evidence to show that any completed work met with building regulations at the time.
Download the application form to apply to regularise building work, details of where to send the application are on the form. Please contact the Building Control department for a quote.