Starting in September, the French Theia Land data centre will deliver Sentinel-2 images produced at L2A (after atmospheric correction and provided with a cloud mask). The zones where L2A products will be delivered amount to 5M square kilometres and are scattered in nearly all continents. The following link gives you a map of the selected tiles.
A first time series of images acquired in South of France (Provence, Alps), processed with MACCS software, is available on a ftp server to help you get to know its file format and test its quality. Everything is explained here. Further improvements, such as a much enhanced cloud shadows mask will be added before the production starts.