Found it written on the box 10 secs after posting!
They need to be torque'd up to 15nm (as was written on the box).
The job is a pretty easy one for anyone attempting it, but is WAY easier if you remove the radiator and do a coolant flush at the same time! Will certainly be taking the radiator off again shortly when I come to do the injectors in a month or so.
Happy to report that was down on 2 glow plugs so the cold starting should be much improved now!