Here’s a recently published research report by the Law Library of Congress.
From the Intro:
This report contains information on laws regulating the collection of intelligence in the European Union, United Kingdom, France, Netherlands, Portugal, Romania, and Sweden. The report details how EU Members States control activities of their intelligence agencies and what restrictions are imposed on information collection. All EU Member States follow EU legislation on personal data protection, which is a part of the common European Union responsibility.
A comparative summary is available here.