Used to be 7 points required - work it out like this.....
I got in to the B.Ed course with 9 points, from 5 Highers. It's probably changed now though.
English is a must and maths preferred. Try to get experience being a helper in a primary school one afternoon a week, maybe in your 6th year. When applying, the powers that be will be looking for some experience, no matter how limited.
Good luck. It's a good job - infuriating at times but rewarding more often.