Create functions in the code under the report properties:
Page Number:
Function PageNumber() As String Return Me.Report.Globals!PageNumber End Function
Total Pages:
Function TotalPages() As String Return Me.Report.Globals!TotalPages End Function
Access it in the body via an expression:
=code.PageNumber & " of " & code.TotalPages
Link: https://stackoverflow.com/questions/4758793/access-page-number-in-report-body-in-ssrs