Is SQL Management Studio 2012 avaliable, without Engine itself

I'm assuming you've remembered to include the instancename (server\SQLEXPRESS)?

Try to create an ODBC against the same server. If you get the same error; create another ODBC, but use regular "SQL Server" driver, and on the "Client Configuration" settings choose "Named Pipes".

Also, SQLChickens tip about making sure the SQL Browser is started on the server is valid.

Also, try using IP-address instead of the NetBios name.

I haven't looked further into this but can confirm this is what happens - perhaps due to the service pack levels differing? (installed instance being SP1 and the tool installer not)

I just used control panel and changed the installed SQL 2008 to remove the database service instance.

Then I installed the MSSQL 2008 Express edition that includes the standard tools - and the option for management studio was there to check... not an elegant solution but it worked - so I didn't bother to figure out the original problem.