GCSEs are quite important, obviously not nearly as important as A-Levels but still important in their own right
If you get less than what you were hoping for your ego might suffer especially if people around you achieve better results
You'll have plenty of time to relax and procrastinate in the summer, now is the time to make a final effort with revision to make sure you won't be disappointed with yourself on result's day
Good luck and I hope it all goes well