As has been said so many times on the forum, the Td5 Disco's diagnostics system is NOT OBDII compliant, consequently any generic scanner might give you a list of fault codes but can you be sure that they are actually going to make sense?
I looked at Nanocon and Hawkeye when I was ready and came down on the side of the Nanocom.
The Hawkeye's software wasn't up to the Nano at the time but since then it has been upgraded.
I would still go for the Nanocom though.