If you're seriously considering either economics or compsci, I'm not sure why biology is a factor on both lists. It's a well-regarded subject but is of no particular relevance to either course.
Surely the obvious option would be maths, physics, economics, and computer science? Covers all the bases.
Pretty sure computer science courses do not generally expect computer science A level (plenty of schools don't even offer it), just maths A level, so there's nothing really to choose between the two options you've given.