The great thing about OSM is the currency. New developments will be added more qucikly. But for completeness and consistency Ordnance Survey data will just be better. And they do have a free building dataset, and even pre-generated vector tiles.
Even the OS data -- at least what I can see in Aurora -- might not be as complete as where someone has taken an interest in a new development, such as one near here. The OpenData building shapes are a good start, but they appear to have been auto-generated, and usually need correcting from up-to-date satellite imagery, if not a survey.
