No Being Able To Do Required Practicals Due To Phobia Watch
Think about seeing a therapist. Hypnosis is often very helpful in dealing with phobias.
As above, if you aren't currently, I would recommend speaking to a professional about it (which you will probably need to do in order to get some supporting documentation for the exam board to consider the extenuating circumstances anyway). They might be able to also help you manage symptoms in the short term and potentially address any root cause of the phobia. Even if not, as above you will probably need to talk to one to get a formal diagnosis and documentation confirming your circumstances.