I only do history and it obviously consists of a lot of work. The memory game in History is pretty hard to nail down initially considering you are studying hundreds of years worth of historical events, however the most important part personally is getting down essay technique. In my first history essay of Y12 I got a D, in my second I got an A, just by pinning down where the hell I went wrong. History isn't too bad in terms of workload, but it really just depends on whether you enjoy the topics you are learning. Many people in my class complained about learning British politics, but they ended up loving it at the end of Y12.
(I take History, Eng Lit, Eng Lang and Art, also did an EPQ)