bruffin I am interested in this and asked my DDs. They tick a box on the form to indicate they have a diagnosis. They need to have had a particular post 16 assessment which can be carried out by a qualified teacher assessor, in my DDs case the Dyslexia centre arranged this but I assume school SENCOs can carry it out as well.
My DDs say that their school references only referred indirectly to their SpLDs, though for DD2 they are quite severe, other than implied effects eg "her ability is greater than her modest realisation", her lack of confidence in her ability obviously being related to her SpLDs. However she has very good grades predicted. I don't know if the assessment was sent to the uni. I doubt it since it is all done online and even if a hard copy I doubt they would have time to read it at the stage of making offers given they are looking at hundreds even thousands of applications. Perhaps an Admissions Officer will be along to advise.
However once at uni and with DSA in place the Learning Support Centre (or whatever it is called) will swing into action once the student approaches them. Support at DD1s uni has been absolutely fantastic, not just from Learning Support but also from academic staff who have a far better understanding than most school teachers. For extra time, although she had an Ed Psych report, they did their own assessment with four measures related to writing and four to reading. It was a good deal more sound and objective than OFQUALs latest attempt to limit the number of pupils with access to extra time regulations. She was also assessed for equipment to help her with her problems getting down notes / absorbing information in lectures. They also have a centre where students can access all the latest software that can assist. They really are committed to levelling the playing field as long as the student seeks help