It's for the children that you are a subject leader. You have this responsibility for their sake. Anything and everything you do in this capacity is for them. If you create a long term plan, rewrite a medium term plan, visit a lesson, deliver a staff meeting, look at books – it's all for the children.
It is their right, what they deserve – to have the best art/MFL/geography/maths/computing learning opportunities. The more you know about what is happening, the more you can do what is necessary to make better and better things happen.
And, as do your best to serve the children in your school, you build your understanding of your subject. And your build your understanding of your subject so that you can better serve your children.
If you are doing everything you can as a subject leader to ensure that the children in your school are getting the best possible education in your subject then you will be ready to tell anyone about it: fellow teachers, senior leaders, parents, governors, and yes, Ofsted inspectors. I will repeat: If you are doing everything you can as a subject leader to ensure that the children in your school are getting the best possible education in your subject then you will be ready to speak to Ofsted about it with confidence.
True, your subject may not be where you want it to be on the day that they arrive but if you know its ins and outs then there will be nothing that they can tell you that you don’t already know. You will know the history of the subject, you will know what you have done already to make changes, you will know its current state, you will know what your next steps are and you will also know that which you have put on the backburner for the time being as you have prioritised other things as being more immediately important. This is what matters, not having a perfect subject to present to them.
During my most recent Ofsted experience I was invited by an inspector to co-observe some lessons. Before going in to each room she would ask me what I expected to see in there. This was not an invitation for me to paint an inaccurate, glowing picture of the teaching and learning that would be taking place, but the opportunity for me as a leader to show her what I knew – to tell the truth. In essence, it was a chance for me to say ‘there is nothing you can tell me that I don’t know; there will be no surprises.’.
That’s what you will be able to do with your subject if you know it so well because you want to make it the best possible experience for the children. It's not about having everything perfect, but about knowing accurately the current state of affairs, and having your ducks in a row: the ducks at the start of the line are the things you’ve already done, the ducks in the middle are the things you’re doing now, and the ducks at the end are the things you plan to do later.
And the big O should not be feared – there is nowhere to say that you as a subject leader have to be the only person in a deep dive meeting. Remember that you are the leader of a team – the framework says that teachers should be able to talk about the curriculum, so you don’t have to be alone – subject leaders, teachers and senior leaders should all be able to be present. This will demonstrate a shared responsibility, as you present that shared knowledge to inspectors, acknowledging that subject development is not the preserve of subject leaders, but of the whole staff.
For more on this, here's some recommended listening: