One possible way might have been no Munich agreement resulting in the Soviet Union continuing to provide fighter aircraft or a genuine arms embargo enforced by Britain and France by stopping and searching ships bound for Portugeuse ports or cooperation from Salazr (unlikely).
The consequences? Should war have still occured Spain joins in on the allied side declaring war on Italy in retaliation. Germany lacks a friendly neutral ally and has no limited facilities provided for U-boats and provides no intelligencve information for Germany. Operation mincemeat doesn't take place