Constitutional law is very interesting as it is the very basis for the functioning of a democratic liberal society, to develop your interest further I would recommend "the Rule of Law" by Tom Bingham. He explains the basics of Constitutional law and the concept of rule of law in lucid and really easy language. Bingham a judicial hero of sorts. EU law is primarily linked to British constitutional Law in the Human rights Act, 1998 which tries to invigorate the European Convention on Human Rights in the British system.
Caution-too much to study but it might be worth it, depending on you