Intro: 70cm and 80cm
British Novice is 90cm and then it works up to 1m20
Theres also amateurs which go from 90cm to 1m20
Or trailblazers, which is sort of a stepping stone - 70, 80 and 90cm, but its free, and would appear at first glance to be more relaxed (correct me if im wrong!)
ETA this is for seniors - will go and look up juniors now!