While would have used the code below to create the message, which will retain the user's signature, are you saying that you want the attachment that you have already attached to the message to include the date and time from the subject of the message? If so, that's not going to happen.
If you want the date and time in your pdf name then you should get the user to enter the time and date in your userform and apply them to the pdf before you create the message (and don't try and use the '/' character in that filename).
As you are using a userform to create the message, there is no point in getting the user to mess around with the created message. That message should be complete.
Code:
Private Sub sendreport_Click()
Dim OL As Object
Dim EmailItem As Object
Dim olInsp As Object
Dim wdDoc As Object
Dim oRng As Range
Dim Doc As Document
Dim strFileName As String
Application.ScreenUpdating = False
Set Doc = ActiveDocument
Doc.Save
strFileName = Replace(Doc.FullName, ".docx", ".pdf")
Doc.ExportAsFixedFormat OutputFileName:=strFileName, _
ExportFormat:=wdExportFormatPDF
Set OL = CreateObject("Outlook.Application")
Set EmailItem = OL.CreateItem(0) ' 0 = olMailItem
With EmailItem
.To = "tyrone@email.com.au; main@emails.com.au "
.Importance = 1 ' olImportanceHigh
.Subject = "Security handover report, for duty completion: 00/00/00 - 0000-0000"
.Attachments.Add strFileName
Set olInsp = EmailItem.GetInspector
Set wdDoc = olInsp.WordEditor
Set oRng = wdDoc.Range
oRng.Collapse 1
oRng.Text = "* SECURITY INSTRUCTION = Change date/time above in end of subject line + Add designation/name to signature area below + DELETE THIS LINE OF TEXT" & vbCrLf & _
"Dear Team Member," & vbCrLf & _
" Please find attached the Security Handover Report' for the completed duty period. " & vbCrLf & _
" TYRONE= TEST: AUTO Stationary is applied Y= EDIT VBA Remove this text & UPDATE .-TO-= Email Recipients list, Master file be kept in OneDrive with a desktop shortcut link on PC desktop. Fix to save with automated in both local store file and one attached<<< REMOVE-AMMEND THIS TEXT Before going live"
.Display
End With
Application.ScreenUpdating = True
Set Doc = Nothing
Set EmailItem = Nothing
Set OL = Nothing
Set wdDoc = Nothing
Set olInsp = Nothing
Set oRng = Nothing
MsgBox "Please change the *DATE* & *SHIFT TIME* in the subject line of the email. Add your Designation/NAME to the signature in the email bottom and hit send... Word is going to save and close hit OK."
ActiveDocument.Close SaveChanges:=wdSaveChanges
End Sub