I got office program. This program stores his data in SQL Server 2008 Express, but there is no management studio and no sqlcmd. How can i get into pure SQL tables, to use them in my plugin.
You can download SSMS 2012 or 2014 which is a full seperate download and then use it to access tables, etc
link: ssms 2012
can't comment on what/ how your plugin is.
You can download some free administration tool, for example, SQL Manager Lite for SQL Server. It does not require additional client libraries.