AFAIK you can’t tell a live template to add namespace imports automatically.
So the workaround is to Alt+Enter one of symbols belonging to an unimported namespace, and choose a quick-fix to import it.

Is it possible (without digging to deep into code and macros) to add a Namespace include if you insert a specific template.

in the above this would add a “using log4net;” among the other using’s in a file the first time the template was invoked.