RNS-E - which disc/update?

[BenB72.0TFSI]

Hi all
I have just purchased a 2007 A4 Avant TFSI with the RNS-E sat nav head unit.
Unfortunately the DVD nav disc is missing.

I am not sure which disc to buy as I don't know whether any previous updates have been performed.
Do all the newer discs contain the updates as well as Nav?
Can I just buy a newer disc (2013) to update and run maps or is a separate update required first?

Thanks
Ben