Can anyone help? I have been googling away and playing around with fields and expressions trying to get this to work...

I am trying to change the page numbering format at the end of a document. Section break at the end of the content and then the appendices start. New page numbering but rather than start from '1' I am trying to make it start from A-1 or A.1 (or something similar but trying to get the field sorted first).
I realise I could just add the text before the number but i want it to be picked up in the TOC at the top of the document.

Any thoughts? I assume there is some nifty fields trick, inserting some string constant to prefix the page number but cant work out how.

Thanks for the help (I hope!)