The development environment and target environment are different. In your case, you want to develop apps for Ubuntu Touch (currently based on 14.10, target environment) on your 14.04 machine (development environment). You can do so in 2 ways,
Create an Ubuntu Emulator using Ubuntu SDK. This will allow you to create apps in 14.04 and then deploy them to the emulator running ubuntu touch.
Upgrade to 14.10 and future versions of Ubuntu to be able to run on the desktop.
The first method is fully supported by the Ubuntu SDK developers and the easiest way to develop for ubuntu touch. This method is very similar to the android development strategy where developers usually test their app on different versions of android using emulators.
You can find clear instructions on running your app on the emulator here.