I don't believe it is a
requirement for the investigation meeting notes to be provided at the end of the interview. The ACAS guide on investigation meetings says that at the end of the interview the interviewer should "
explain that the interviewee will be provided shortly with a copy of their witness statement for them to check and confirm that it is accurate".
By all means contact Citizens Advice for support. What I can say is that I work for Citizens Advice and if your Dad was coming to me at this stage I'd say that he needs to wait for the outcome of the investigation. There's nothing more that he needs to do at this stage. I'd also be suggesting he reads the information on our website and the ACAS website (there is a lot!).
This link is to the first page of the CAB advice, notice the following pages are linked on the right-hand side:
Find out what to do if your employer takes disciplinary action against you.
www.citizensadvice.org.uk
Some of the ACAS advice is written from the point of view of advising the employer what they should do:
How workers and employers can use formal procedures. Disciplinary. Grievance. Investigation.
www.acas.org.uk