Besides advanced weapons research and development, the OSA has very little information on what goes on inside the SWF. Kreisau Circle intelligence does suggest that the SWF contains a U-boat pen that may be used as a debarkation point for another of Deathshead's secret research projects, although we have no idea what that might be at this time. The bombing raid has made a mess of communications topside, so you should be able to enter the facility without their knowledge.