When am I most at risk of fret buzz, when my neck is too far from the strings or too close to the strings?
I have already tried both options by changing my trust rod .
I am a beginner and know that it is definitely down to my technique, but I would still like to know what is best , strings close to the neck or a bit further away.
In my opinion it should be straight or slightly concave, never convex. Once the neck is straight you can set the action (distance or separation between strings and the neck) on the bridge to suit your taste. I like as low action as possible without extreme buzz, but I come from an electric guitar background. You can also adjust the action on the nut, but I don’t recommend doing it as a beginner as it involves filing/sanding and it’s not reversible (well you can always change the whole nut but that’s even more work and often done by professionals)
Action will affect playability (lower action easier fretting) and also tone/sustain, and buzz of course.
Maybe as a beginner it’ll be better for you to set up a higher action so you’ll train your hand muscles and if the instrument buzzes you’ll know it’s your fault and not the set up.
Thanks for the advice 
With no tension on the strings, get the truss rod adjusted so the fingerboard is totally flat. Then tune it. Tuning tension will put the slight bend where it should be. Pluck each note on all the strings and if one fret has a buzz make note of it on paper. After all are checked, if many buzz then the action is too low. Another thing to check is pickup height. Fret the highest note on the strings, there should be a noticeable gap between the string and forward pickup. If it is touching the strings, lower it a little at a time with the screws on each end until there is a gap.
It’s perfect now, thanks Shaker for your tips, learned something new again.