Tutoring is very valid experience as it requires you to prepare lessons and break down topics for students, however it can't be a replacement for seeing/knowing how to manage a class of 30! Any other experience with young people is perfectly valid too- teaching isn't just about standing in front of the board, the pastoral side is important too. Observation is generally all you will get to do in a school before your course, as you obviously can't be expected to know what you're doing. It could be that if you're somewhere for a longer amount of time the teacher may let you lead a starter with the class or work with a small group of students, however it's vital that you observe what's happening in the classroom before you try anything out for yourself. I was lucky enough to get to do some activities with students when I was doing my observation, and even taught a lesson with a cover supervisor present as the teacher was going to be absent- she did leave work in case I had to stop for whatever reason. But I did know the school as my sister was in that class! I'd already been an English assistant abroad so did have whole class experience and I'd already gained a place on my course so that may have had something to do with it. But to be honest the practical experience of teaching a lesson at that point wasn't too useful- I learned more from being in the classroom with an experienced teacher. I always helped out where I could (very aware that it's boring watching for an hour!),but it was definitely watching that I needed to do.