Daewoo Matiz (2001 mk2) DLC position - circlip
Where is the Data Link Connector to install the diagnostic tool? I've been under the dashboard with a torch and cannot find anything that looks like a vacant 16 pin connector. engine compartment - ditto.
Daewoo Matiz (2001 mk2) DLC position - Screwloose
ciclip

In theory, it should be either just under the fascia on the passenger's side near the pillar; or directly beneath the steering column. However, these things often aren't where they are supposed to be and it's very easy to waste anything up to an hour playing "hunt the socket."

It's also possible that if it was built before 2001, your's hasn't got a 16-pin EOBD socket, but a Daewoo 12-pin rectangular one. Don't try any pin-shorting tricks on these, as they're listed as scanner-only.
Daewoo Matiz (2001 mk2) DLC position - John24
On the manual I've seen, the DLC is in the front passenger footwell. Unfortunately, doesn't show what it looks like.
Daewoo Matiz (2001 mk2) DLC position - circlip
Thanks for the input lads. I did eventually find it in the passenger footwell directly underneath the glove box. It faces down and is covered with a black plastic clip-on cover, so it does not look like one would expect until after the cover is removed. All I need now is a diagnostic tool...