I didn't write "see spare paper" on my answers in my exam

So long as you wrote your name, centre number, candidate number etc then it will be fine. They will check!

Fr I did the same not checking there's extra lines. It was a pretty packed exam, loads to write in a short amount of time.

It'll all be sent to them, and they should check all pages of your script.

Off the top of my head scripts with additions are specifically flagged when the scripts are processed for online marking (they are all processed/checked by hand I believe) so that it shouldn't be missed, though I can't remember where I read this.