Should I secretly record a meeting to prove I'm being discriminated against?
No.

Such action should be the very, very last resort, and only undertaken if you have taken legal advice on whether it is advisable to do so.

As a UK student, you should have support available to you from the Student Union, which will almost certainly include disability representation.

The Student Union will be able to advise you on how to proceed on this matter, and possible provide you with a third party representative to join you at any meetings you have.

Also, you mention emails that exist 'about you.'  You are within your rights to request these to see what they say by making a freedom of information request.  Again, seek advice first before undertaking this action.