UNESCO have produced updated international tecnical guidelines on ‘comprehensive sexuality education’ – these include detailed and very useful curriculum planning material.
The UNESCO guidelines organise sexuality education around 8 concepts, the first of which is 'relationships'. For each concept there are a number of key ideas. Each key idea folds out into a series of learning objectives. These are organised by age group, starting with 5-8 year olds. Try browsing the key ideas to map against your curriculum and see how the learning objectives can inspire new material for your RSE programme.