Vibration 1500-2000 rpm

I don't know if i'm being a 'nervous nelly' but i seem to be getting viration at 1500-2000rpm when in neutral.
I've recently had a service, including cam belt kit, spark plugs and coil packs.
Am i just thinking the worst, i can't seem to remember it before, but i could be wrong.
Also there is a bit of juddering when cold, i'm hoping this is not the clutch, cos it can't be the plugs or coil packs!

It is quite possible that they fitted the wrong grade of spark plugs.

I did the plugs
NGK, no adjustment required, hopefully
Ordered direct from them too

To have a mismatch only at a certain rpm then I'd be more suspicious of your cam belt change and suspect they got the timing wrong- yet another one as it seems to be very common that garages guess and don't check the timing is set up properly BEFORE they give it back to the customer

If you noticed it immediately after the cambelt change then there's your answer