Depends a lot on caliber of students and what information you want them
to know, but in addition to Speck, which several 'net readers have
already suggested, try the following:
R. K. Webb, Modern Britain
Walter L. Arnstein, The Age of Aristocracy; Britain Yesterday and Today
T. W. Heyck, The Peoples of the British Isles [though my students found
this very simplistic]
Jeffrey Auerbach
Department of History
St. Mary's College of Maryland
jauerbac@oyster.smcm.edu