I want to create a view whereby it does not include any items which does not have the 'next review date' as blank, i.e. only includes items which have this field populated. How do I say blank to a SharePoint? It does not recognize  or [blank] or "".
Create a list view and set the filter; where date time column is not empty (see below)
the view's filter will be: 'next review date' in not equal to [leave it blank - don't write anything]