I'm not autistic, but I am disabled and at QMUL.
I do BA History, just finished 1st year. My lectures have been very supportive with my disability.
When I applied, I disclosed a disability and the QM DDS reached out to me to offer a meeting to see what they could do to support me. You can have it online or in person (I did it online).
They set up a Student Support Plan for me. This could include access to rest rooms, able to leave lectures/seminars with no questions asked, easier way to get EC's for assignments or anything you think you might need. They will offer things you might want, so don't think you need to know immediately.
They can support with a DSA application. I did mine myself though. If you are assigned a mentor etc, they may provide it and DSA pay them.
In terms of welcome week, I know they offer a campus tour for neuro divergent students at a much quieter time. There are also quiet areas on campus for you to go to.
With DDS overall, they are quite overwhelmed with too many students and not enough staff, so you sort of need to keep on top of what is going on. Especially DSA applications as they are a bit complicated and quite a long process. However, if you reach out for support, then DDS will give it to you.