Hi there,
I’m a SENDCo across 2 schools also. Sorry to hear you’ve been given this task and aren’t a member of SLT. In the first instance I feel that it would be important for you to address this. It’s extremely important for the SENDCo to be a part of the SLT especially f they are to have a strategic role across the school and be able to make decisions re staff deployment and development.
Perhaps a conversation is needed with your line manager in the first instance. Good luck.