Fluffybunny - I would just ring the Disability Officer and explain that things are a bit tricky and you'd like to get support in place over the summer so that everyone is clear about what is going on next year.
She (for it will be a she) is there not to generate paperwork but to make things work in reality. Go to see her. Talk frankly about possible scenarios that might arise during the rest of your studies.
Be positive but firm about the support you might need.
You could also ask her to put you in touch with other students with MS, or with visual impairments, so that you can get a handle on what they have won in terms of support. Their tutors might well be able to offer support to your tutors.
Go to your favourite tutor, whatever their specialism. Prevail on them to be your advocate.
If they want to help (but also if they sound unhelpful), tell them brightly to seek support from their Subject Centre (part of the HE Academy) which has produced this report.
You could also show them this list The DEMOS site listed is particularly good.
The DDA is cleverly designed: inertia is prosecutable. They can't 'not get around' to changing stuff. They can't presume that a one size fits all method of examining provides a level playing field. They can't leave it all up to you.
Once you have disclosed your disability everything is up to them.
The question about whether you are fit to practise borders on discriminatory. It suggests that they are thinking 'how can we get out of helping.'
Ring the MS society, or the soc. of radiographers and get a definitive 'of course Fluffy can practise' from them.
Sorry to suggest you'll have a fight on your hands. You shouldn't and hopefully their initial response is a bit panicked rather than anything else.
Let me know if you need any more help of course. I haven't got CAT, but I'm generally loitering around on the August 08 postnatal threads.
If it helps at all, I knew nothing about disability issues until my students demanded support and now I'm passionate about all of this as you might be able to tell.