I'm doing Maths, Further Maths, Physics, Geography, Economics and General Studies. Workload is fine if you just get down and do it.
But as other people have said, just take it as it comes, if you find it too much after a term, drop the one you prefer the least.
h
EDIT: Also don't listen to the people saying drop this, drop that etc. Chemistry and Maths are obvious essentials. Further Maths is becoming essential for all engineering as A-Level maths is not as difficult as it used to be and physics shows that you have the science skills. History is a great counter to this as it shows you can also write essays, think in a non-scientific manner and generally give your application a more balanced feel.