As a supply teacher, you should find that work has been prepared for you. Sometimes however, this is not the case. It doesn’t happen too often, so don’t worry too much about it, but having a handful of great, adaptable supply teaching ideas up your sleeve can help calm your nerves, increase your confidence, and improve your chances of being invited to do supply work again!
As for other ideas, you might want to start by writing a literacy lesson plan based around one story or poem (look at the 3rd category in the shop for inspiration). Then think about how this could be adapted to each year group, each ability.
If you do this exercise properly, it should give you the confidence you need to take it into any classroom. Don’t sweat the small stuff: if no planning has been left, the Headteacher should be suitably embarrassed and will not be looking so closely at your planning that they notice you haven’t included any visual stimuli for the visual learners!
When you’ve brainstormed that lesson idea, see if you can eke out a numeracy / history / geography idea from the same story / poem – you should be able to find something that’s not too tenuous!