To ensure that you have a verbatim record of a disciplinary hearing you could record the meeting on an electronic device instead of taking handwritten notes. But, beware you can’t automatically record a disciplinary (or any other) hearing on an electronic device.
You must seek the employees express and prior consent to the recording before the meeting begins. If they refuse, you cannot go ahead and record the discussion against their wishes. Doing so would not only potentially flout Human Rights Laws, i.e. the right to privacy, it would also breach the General Data Protection Regulations (GDPR) which states that consent must be freely given.
If the employee gives their consent the recording may go ahead. However, they are entitled to a copy of the recording and you must continue to process it lawfully under the GDPR.
Handwritten notes of a meeting need to be fair and accurate reflection of what was said, they don’t have to be verbatim. They are also covered by the GDPR, but you don’t need the employees consent to take them. In this scenario you can rely on “legitimate interests” which is one of the lawful bases for processing personal data. The employee is entitled to a copy of your handwritten notes and any typed-up version.