When you're doing past papers, you shouldn't need a formula sheet anyway. The point of exercises is to 'burn' the formula into you so you don't need to look up the method anymore.
Like for example, I know my sin and cos and tan expansions, I know my product rule, quotient rule... etc. etc. etc.
If you do enough maths, you don't need to look it up anymore. I remember when I did circle geometry and at first I was fully checking up all the 20-odd 'properties'... but after a week or so, I had most of them remembered and later on, I didn't need to look up any pretty much.
That's what you want.