Urgent medical school appeals help- failed resit

I have passed my semester resit but failed my OSCEs by one station. I am completely distraught as because I didn't submit prior mitigating circumstances, I am to be excluded from the programme.
How likely is an appeal to work in my favour?

To give a bit of context, I have a lot of family issues surrounding parental abuse, which have obviously affected mental health. One of the main reasons I didn't submit mitigating before is that I was extremely worried they would check my devices (which they have done in the past) and find out what I had written about them.

I submitted a referral for an ADHD appointment in March (prior to exams) but due to NHS waiting times I didnt get an appointment. I have since had an appointment with a pyschiatrist and have been diagnosed with ADHD.
The pyschiatrist has written a letter outlining my diagnosis and how she believes that it would have impacted my OSCEs. I have sent the programme director an email outlining everything that has happened and I am going to forward the letter from the pyschiatrist to them also.
I have a meeting with the pastoral support team at the university tomorrow.
I've explained my situation to the biosciences admissions team and told them I would like to transfer courses and they said they are happy to accept me onto biomedical science. How likely is this to go through, as if my appeal is rejected, I don't want to be left without a course and a university.
How likely is my appeal to be accepted and do I need a lawyer?
Thank you so much