Off to Belgium and France for a months cyclo tourist type stuff end of July. Going to be camping and carrying everything with me. In the past have had bikes with steel or ali forks so clamping low rider racks hasn’t been an issue. Got a new frame but it has carbon forks. Is it safe to clamp onto these do you think?

No

Stresses in a direction it is not designed for and potentially crushing a tube

Got canti bosses? In which case one of these:
http://www.oldmanmountain.com/Pages/RackPages/FrontRacks.html
otherwise you need a different fork.

No bosses so think it’s going to have to be a new fork with braze ons from somewhere. Shame.