If it bothers you that your social life will be effectively screwed, or that you would be less happy doing learning than going out to parties, then enjoy your summer. But equally, there are some of us who are extreme introverts who find being social draining, in which case you should use your off-days as revision/learning time.
Perhaps you could do revision more socially, by going somewhere that you can socialise and revise.
Personally, when I first began my A-levels, the gap between GCSEs and A-levels were so large that I completely flopped the first time around. It was only after having some background (even at D/E grades) and applying myself properly by reading ahead and learning materials pre-classes that I found myself able to concentrate well to achieve high grades.
Some of my friends had done GCSE additional maths, which covers some of C1, so they found Maths A-levels quite easy because they already knew half the content by the time the teaching started, so getting As weren't a challenge.