Grouping Rows by Date & Providing a Total of Groups

Attached is a sample of a column of a workbook that is designed to record evaluation form responses for a charity.

The spreadsheet is used to record all the responses for all the training courses undertaken - but it has come to light that various training courses have taken place for which no feedback forms have been submitted.
Also, it appears some data for feedback forms have been entered with training dates that do not correspond to known bookings.
Also, where multiple training courses take place on the same day - the feedback data is sometimes all being entered as one course, not separate courses.

Currently, I am going through the workbook and literally trying to correct this manually. And I have at least a dozen more workbooks to go through to investigate and identify missing feedback.

I was wondering if there is a way of automating this process as follows:

A method of searching the column containing dates and grouping them together, whilst also creating a total of how many separate date groups have been identified.

We can then use this total to compare with the bookings in the calendar to verify how many training sessions are missing feedback forms.

Many thanks for any suggestions or help.