School not providing access arrangements

I'm a year 13 student soon to sit the a level exams, all of my exams are in June.
I got diagnosed with ADHD around a bit more then a month ago and I immediately contacted my SENCO and head of house/teacher,
after waiting for a long while for things to be sorted and for the SEN exam coordinator to speak to me (past the 21st of march deadline) by that time she and my head of house/teacher had already mentioned something about a seperate room to sit my exams in, by this point on the 26th of march they mentioned it was too late past the deadline for me to get extra time but still mentioned something about a seperate room.
I then asked this SEN teacher multiple questions (e.g "do I need to go speak to my teachers about my diagnosis and ask for in class arrangements?") and she told me I didn't need to do anything and that she will sort out support.
After a month of waiting I get no kind of response or action plan or EHCP and so I decided to email her and at least see what room I would be in for the seperate exam sitting because classroom support is now useless.
She then emails back saying:
"Exams concessions are based on your normal way of working (NWOW), and I require substantial evidence of this to process any arrangements.
Unfortunately, your teachers have not identified a separate/smaller room as your NWOW. As you sat your GSCE’s, and mock exams, I do not have the evidence required."
And now I litterly have no support at all.
1.) How am I supposed to have evidence for me being supported for ADHD when I wasn't diagnosed for ADHD up until a month ago.
2.) It being too late for extra time is a lie it litterly says on the JCQ access arrangement document
"Late applications on account of a temporary injury or impairment, or a diagnosis of a disability or manifestation of an impairment relating to an existing disability arising after the published deadline are permissible. Centres must process applications as detailed in Chapter 8, section 8.3 using Access arrangements online where required."
3.) Their is clear and repeated evidence of me either: i) asking in lesson support from my teachers pre-diagnosis, ii) Trying for over half a year to get the school to even consider sending a referral for my ADHD assessment (they didn't and i had to beg the GP by myself).
Im honestly at a loss for what to do, I'm gonna have a chat with her with my parents next week but other then that I'm clueless about what else I can do.
Any advice? I don't really need extra time because I rush everything anyway but a seperate room would be the most perfect support arrangement for my symptoms of ADHD.

hey so this was my exact struggle ! you can get rewarded i think an extra 1 or 2% in all of your exams is you plea to the exam board. you can also get special consideration during your exam marking. i highly recommend you bring in all of the proof that they have to give you your separate room, and even dramatise your struggles in the hall. they should do it, they have to. but it’s extra effort they cannot be bothered giving. it does suck that you have to fight so hard for yourself for such a small yet impactful thing. but don’t stop nagging until they give in, it’s one of the only ways they’ll listen to you 🙁. as of getting the ADHD diagnosis, i get that too. my college also said they would refer me, and that the wait was about 18 months for first appointments. 9 months later i return and find that i was not referred because i “didn’t ask” so i paid to get it done privately (my family do not even have that kind of money, i live qualifying for contextual offers just on household income). and since january 2nd, i’ve been waiting for my first medication appointment with the nhs. two months of waiting and nagging i THEN get told it’s a 12 week waiting list and i should hear from them by the end of april (it’s may ! still haven’t heard a thing.) so beside the point. you’re not alone, nag them like crazy and they will have to give in. threaten to take them to small claims court if you have to (obviously don’t go through with it) or to the board of your school.