If you're looking for a low content A Level, you're going to be vaguely out of luck. However, I can say that Physics is relatively content light (most of it is just calculations) and Further maths, if you're good at maths, extends nicely into being about 1.5 subjects worth of work.
Personally, if you're looking for a distraction A level, Literature is a lot of fun if your school studies an area you are interested in. Literature is surprisingly low content if you are smart about it.