I have just received an RTL-SDR V3 dongle. From reading, I think I might have to do some setting up the dongle to work with our tracking systems. Will be using it with a new PI3 B+. What do I have to do to set it up or is it plug and play (I think not ??)
Yes. This is also possible if you are upgrading from a Pi 3 to a Pi 3B+.
Before you move to Pi 3B+ you need to run
sudo apt-get update
sudo apt-get upgrade
This will grab the OS changes needed to run the stock piaware SD card image to be useable on a Pi 3B+.
As far as I know, just using the stock piaware image will not boot on a Pi 3B+. You need to have a spare Pi 3B to update the OS first or follow what I wrote above.