Where to start
If equations worry you, start with Equation Rearranger. It takes you through changing the subject and then using the right units. Unit Sprint is a quick way to get prefixes and conversions fast and right.
For a topic you are revising now, pick the game that matches it. Forces, electricity, waves, energy and radioactivity each have their own game.
Look up an equation
Every physics equation for GCSE has its own page with a calculator that shows the working. Start at the physics equation sheet, which also shows what each exam board lists.