Your nText column will may have values that excede your varchar limit.
Depends on your collation as to whether or not string comparisons are case sensitive. You can always override the default collation in the query itself:
use northwind
--case insensitive select notes from employees where notes like '%English%' COLLATE Latin1_General_CI_AS
--case sensitive select notes from employees where notes like '%english%' COLLATE Latin1_General_CS_AS