I used to be IT manager at a junior school working three full days a week. When I retired last year I wasn’t replaced, so the stuff I did now has to be done by a TA in between her work in class - this is likely to be the case in more and more schools as the cuts bite.
When we had student teachers, I would give them access to one of the student laptops from the class set, and a login to the school system, plus any online sites their mentor thought they should be able to access.
I would do this as soon as possible after they arrived, but ‘as soon as possible’ was a variable that depended on how many teachers had had problems with their laptops during the holidays, how much help the office staff needed with getting the new pupils on SIMS, the online payments system, and any other online sites they needed, and whether any other problems had arisen during the holidays (almost always)so I might well not get around to the student teacher until they asked me for access. And that was with working 22 hours a week, so it’s not surprising nothing’s happened if the IT support is being done by a class TA in their ‘spare time’. Ask your mentor, or in the office who deals with IT support, or have a look at the staff list if you’ve been given one to see if additional roles are listed.
In some schools they may not even have any internal IT support, it may be done by an external company who may only visit once a month or so unless otherwise contacted.
Basically, you need to ask, rather than wait for someone to tell you.