I fully agree with Joanne. I’m not a SENCo but I am qualified to carry out the psychometric tests (I have the CPT3A). Getting information from teachers is challenging sometimes so I send out two referral forms to complete with any concerns. Use these along with any data you can find such as CAT/SATs, progress reports, pen profiles, information from the student/parents etc. Build up a picture and then test them. I assume someone external is coming in to test? If so they will have a full range of tests to highlight all of the student’s difficulties.
I am more than happy to send you the referral forms I use if you want to send me your email.