Study support IME is variable but often excellent (I've taught at a couple of UK universities and another elsewhere; I'm dyslexic and work with a lot of dyslexic students). If possible, he should see if he can set up a meeting asap (is he ok with zoom?) to discuss this with them and explain he's overwhelmed.
He could also talk to the people teaching him directly. Again, people are variable in their knowledge of dyslexia, but his tutors will want him to succeed. Frankly, it is not at all unusual for any student in their first term to struggle massively to write university essays, especially if they've done non-essay subjects at A Level.
All the things you're saying he struggles with are common, normal problems that other students will have too. I know you're shocked and he's struggling much more than his peers, but it's useful to keep in mind that he's got loads of time to learn.
When I teach students who sound like your son, I would concentrate on getting him to slow down and break everything into small tasks.
- First he needs to understand the question. He might try to write down, or record, what he thinks it is about, and what is confusing. It always interests me how often students say they don't understand the question, but don't fully process or recognise that they haven't understood a key term, or they dimly realise they don't understand why the question would even matter, but they can't figure out how to say so.
At this stage, no response is silly. If he can take a really good, long time to figure out what he thinks the question means, it will streamline the whole rest of the process. If he is allowed to email his tutor to check things, so much the better (he should be super-polite doing this, and clear that he's trying to keep on top of his dyslexia, just in case the tutor isn't actually geared up to respond to questions prior to marking the essay).
- Second, once he's got the question as thoroughly understood as possible, he needs to select a realistic amount of reading. Has he been given a list? If so, is he meant to be reading all of it (quite probably not), or just some of it? He needs to prioritise. If he's very much held up by reading speed, this might be an ongoing problem, but initially at least, a deep breath and reading a manageable amount is the best approach.
Third is learning how to take good notes from the reading, how to go through these to glean the important info, and how to relate that back to the question. This will often mean ignoring things that authors of his reading matter say are very important, because those things are not relevant to the question. IME students think this sounds simple, even patronising, when I put it like this - but they all find it hard to do. And so do I. So number 3 requires a lot of practice.
Fourth, he needs eventually to learn to reference. Unless his essay marks go towards his final result, here, what he should concentrate on is simply making a good effort to write down the names of all the material he's read, and make sure that info gets into the essay in some form. Worrying about precise details isn't, I would suggest, the priority here: the important thing is communicating where he got his ideas/secondary materials from.
I don't want to make this very long post even longer, but I hope it's a little bit useful. Please don't let him feel too daunted! Honestly, it's all doable, he got there, so he has the ability to do the course.