Hi there, new to Phantoms, so just purchased a P2 version 3 with new transmitter. I have a chance at getting hold of a H3-2D gimbal! Is it possible to simply connect the ribbon to the gimbal without using the GVU that is with the gimbal?

Well sure, with enough determination I'm sure you could.  What I suspect you're really asking is, will it work.  Uhhh... no.

Just to clarify, you have a Phantom 2 v3 - plain model that came without any gimbal, correct?  And when you refer to a "GVU" I'm guessing you're referring to the Gimbal Controller Unit (GCU)?

The two different gimbals require a GCU that is specific to each unit.  You can NOT use a H3-3D GCU on a H3-2D.