The calculus chain
The calculus chain

In constant acceleration questions you could use SUVAT, but with variable acceleration the acceleration changes with time, so SUVAT usually does not apply. Instead, calculus links displacement, velocity and acceleration.
Step-by-step lessons on Edexcel A Level Maths Variable Acceleration, covering 11.1 Functions of Time, 11.2 Using Differentiation, 11.3 Maxima and Minima Problems, 11.4 Using Integration, and 11.5 Constant Acceleration Formulae. Each one builds up to exam-style questions. Build fluency with the core pure algebra and calculus toolkit early, since almost every mechanics and statistics topic on the course depends on it.