I think your going to find A Levels much harder than what you think. I did really well at my GCSE, but in my first year of A-Levels i got DDEU. Admittly in my 2nd year I worked really hard, didn't leave the house for 3 months and I got decent grades, and that was with 3 subjects. I dropped the U, but i underestimated how much work was required to do well. You don't need to do 6 A-Levels, unless your going to do 6 degrees in each of the subjects.