Sounds like you're out of Freon to me.
This could be due to just a long period of disuse, thus the seals have dried up, or it could be a more serious problem.
Anyway, any automotive A/C place can help you to both pressure test your system and to refill. You probably need to know the amount the refill as the A/C place won't have your car in their list. I forgotten the quantity right now, but it's in the service manual. Possibly also in the user manual.
The connection points for refills/ pressure tests are on the right hand side in the engine bay, and can possibly be accessed through the air scoop on the right hand side. (Only done this with an Exige where that is by far the easiest way to access the connection points)