need to put full stop/period before footnote mark

A number followed by a period is not a standard Word footnote reference style, so the period after is most likely added later and is not actually part of the footnote reference.

Or maybe the OP isn't referring to a footnote reference style, but to the document's punctuation...

The following macro ensures all Footnote & Endnote references are placed afterany applicable adjacent punctuation marks. Any preceding space characters are also deleted.

Sub FootnoteEndnoteFix()

Dim FtNt As Footnote, EndNt As Endnote, Rng As Range

With ActiveDocument

  For Each FtNt In .Footnotes

    Set Rng = FtNt.Reference

    With Rng

      'Eliminate any spaces before the footnote

      While .Characters.First.Previous.Text = " "

        .Characters.First.Previous.Text = ""

      Wend

      'Swap the footnote/punctuation, as applicable

      Select Case .Characters.Last.Next

        Case ".", ",", "!", "?", ":", ";"

        .InsertBefore .Characters.Last.Next

        .Characters.Last.Next.Delete

      End Select

    End With

  Next

  For Each EndNt In .Endnotes

    Set Rng = EndNt.Reference

    With Rng

      'Eliminate any spaces before the endnote

      While .Characters.First.Previous.Text = " "

        .Characters.First.Previous.Text = ""

      Wend

      'Swap the endnote/punctuation, as applicable

      Select Case .Characters.Last.Next

        Case ".", ",", "!", "?", ":", ";"

        .InsertBefore .Characters.Last.Next

        .Characters.Last.Next.Delete

      End Select

    End With

  Next

End With

End Sub

To ensure Footnote & Endnote references are placed before any applicable adjacent punctuation marks, change:

      Select Case .Characters.Last.Next

        Case ".", ",", "!", "?", ";"

        .InsertBefore .Characters.Last.Next

        .Characters.Last.Next.Delete

      End Select

to:

      Select Case .Characters.First.Previous

        Case ".", ",", "!", "?", ";"

          .InsertAfter .Characters.First.Previous

          .Characters.First.Previous.Text = ""

          .Characters.Last.Font.Superscript = False

        End Select

Jez:

Did you replace the Style of the full-stop?

Cheers

This half-worked. I now have a superscript full stop in front of the footnote mark, and a normal full stop after. I tried a find-and-replace for superscript full stop to not superscript full stop, with no success. 

Next step?

Give this a try:

1. In Word, switch to Draft view.
2. From the View menu, choose Footnotes. Click just before the first footnote reference in the main body of your document.
3. Choose Edit>Find>Advanced Find and Replace. Choose the Replace tab.
4. In Find, enter ^02
5. In Replace, enter .^&
6. Click on Replace All. All footnote numbers should now be preceded by a period.