Headlights not working, fuse box question.

Good afternoon all,

I am attempting to put a 1986 convertible back on the road that has been out of use for some years, and passed through many poor mechanics/amateur sparkies. After a bit of tinkering, I’ve managed to get it running and replaced the fuse box along the way. All exterior lights are now working with the exception of the headlights and spotlights.

There is no lead going to the M connector on the rear of the fuse box and I believe this may be the issue. Can anyone tell me where this connection should come from and if it’s a critical feed please, as I’m not sure if someone has bodged it previously or if this car never had one.

Looking through some threads on here, I think it should be grey and yellow but I’m not sure if it goes to the light switch, flash switch or what as I don’t have a decent wiring diagram.

There is also an empty relay plug hanging off the main bunch, though it comes from the loom and is a VW one.
Any assistance would be appreciated as I’d really like to get it resolved this weekend so I can move on to trying to get more dash lights working and a stereo wired in.

Thanks,
Mitch.