In the UK, differentiation and integration aren't taught for GCSE maths (to ~16 year olds, last year of compulsory schooling) [1] but are for AS-level maths (to ~17 year olds) [2]
However, students select which AS-levels and A-levels they want to study; students can drop math entirely if they so wish. And some CS departments will accept such students, putting them through a high-speed remedial math course.