Dr Peter Edmunds (Found @edmunds_dr) has shared a more than generous amount of free KS4 Physics worksheets on his website. He has also made a book with more, improved versions (AQA GCSE Science 9-1 Equations Practice Pack)
I Teach Boys (Found @ITeachBoys92) has shared his resources on a Google Drive. I regularly use some of his "Ten Minutes on..." worksheets for quick assessment and exam practice. His stuff is found here.
This website produces excellent Scientific journals that are accessible for secondary students and come with questions to check understanding. We use in our school to develop the student's academic literacy skills.