Disabled Student's Allowance
Since Dyslexia, including Dyscalculia, was included in the Disability Discrimination Act (DDA) it has helped to level the playing field for dyslexics.
We know Dyslexia is not a disability; far from it. But the advantages of the dyslexic thinking style can come with baggage that is disabling. A dyslexic is disabled in the same way as a person whose legs have been tied to a chair is disabled from walking.
The DDA is the tool the government has given us; and because of it dyslexic students in higher education can access the Disabled Student's Allowance (DSA)
If you know you are dyslexic before you go to university it pays to do your homework about DSA in advance. Preferably 18 months to 2 years in advance. The above link will take you to the government website which explains all about who can apply, how to apply and what is required as supportive evidence of need.
Ideally, you should set the wheels in motion at least as soon as you start to apply for student funding -it can take longer to get sorted out and it is most helpful if you can have everything in place when you start your course and don't have to wait most of the first year for equipment and accommodations.
Disabled Students' Allowance will fund whatever support you, as a student, need because of a disability under the Disability Discrimination Act. Your needs will be decided based an up to date psychological report and an interview with a Needs Assessor.