I’m not on SLT and no-one who is on SLT in my schools (I work across two primary schools) does what you say above. In a way it sounds great, someone else taking an interest in what needs doing for SEN but I would also feel my toes were being stepped on and it was being implied I wasn’t doing things properly if someone just started doing this without having any conversation with me. I would see if you can speak with the deputy head and agree between you who is doing what and how it will work – agree who is chasing what and when / should deputy wait for you to approach her if you would like any help with chasing something or are there things that will be her responsibility to chase / would you agree to meet say every couple of weeks to review things and so you could reassure that things are in hand and she could ease off etc. There are definite advantages to having someone taking this interest as could help you out but I would say you should be the one with overall control of these areas, working together with the deputy as appropriate. Perhaps she is trying to be helpful but just getting it a bit wrong.