I know several locals who proceeded with building work only to be caught out considerably later in the day much to their detriment.  Don't overlook the fact that the authorities are happy to concoct any scheme they can think of to fill the coffers in these difficult times and change or introduce laws and regulations and indulge in back-dating.  Independent and qualified advice is worth paying for even if it is only to put a handle on the level of risk you are potentially taking.  (Look before you leap.)

I think there is an equivalent to the law of prescription here but someone like David Piqué might be able to clarify.

Dreams cost nothing... reality usually comes at a price.