British hostory is the subjest which is still more scoring subject then other history subjects , Tauseef haider (css 2004 2nd postion holder) got 152 marks in this subject and he still advise me to go for this subject.and his notes are really helpfull for me .

now regarding books the members had given right book but i will add some of them :

British History At a Glance BY Sheikh MOHD Qayyum.

and British Hostory by V.D Mahajan.

both are good book and offcource encarta would helps a lot.