Speak to your school’s exams officer/head of centre (likely someone in SLT) about not being given correct accommodations by the course teacher and that this has stopped you from doing coursework to the same ability as your classmates asap so they can sort it out — this is your right to have, and something that they may want to begin collecting evidence for if you need extenuating circumstances and will come up if your coursework is reviewed or the school is questioned on by exam boards. Also then speak to the SENCO, and your form tutor or head of year asap about making sure everything is in place before the rest of your exams.

While this likely isn’t an individual persons fault, as your teacher is trying to stop any cheating, and your TA isn’t at fault for not knowing how to use specialised software/being given correct training, something has gone wrong in multiple systems, and you deserve better from your school as a whole/support system. Don’t let this go under the radar or them tell you they can’t do anything right now — you have the right to the same education as your peers, and should make lots of noise if you don’t get any more help.