If you run a VM on Windows, then run a host within the VM, the display drivers presented to the host, are those of virtual hardware created by the VM. Your host, will have no idea you're running a UHD display, unless you could pass the whole device to the host (which could only be done, if the actual running OS, windows, was using a different display device).
I believe if you use VMWare, and have VMware tools installed in the host, you can resize the VM screen, like a regular desktop window. Without tools, you have to specify the display resolution in the vm config file. Looking at an Ubuntu VM I have running under Workstation 10, I can emulate up 10 monitors, each with up to a 2560x1600 resolution. I'm not sure how to have those multiple monitors display on my physical host, but it must be possible.
But remember when you run under a VM, you're not running on your actual machine, the host is running on a virtual host, which you can design as you wish, with whatever hardware you want. If you want to emulate a UHD display, in the host, you'll need a VM that can emulate one (I was unable to find one given a cursory search in google).
If you're just trying to run Ubuntu in full resolution, did you try running rebooting the system to use Ubuntu on a Live CD. It will then use whatever drivers it has installed to use your UHD display, as much as it's able. With the Kubuntu live CD, I've installed Nvidia drivers and tested out a full x display, to be sure the hardware could support running my desktop, before re-installing. Live CD stores modifications to the virtual hard disk in memory, so you have the perception of a normal running machine, without actually touching the existing HD.