I'm currently wishing to draw up my UI for a 2d game, however I'm not so sure what the normal strategy is for creating the images for a UI. Are there any programmes which are specifically accurate for UI Design or is something like Photoshop perfectly fine?
You can use any graphics tool you are comfortable with. I'm not sure what you mean by "Accurate for UI Design". Besides, are you talking about animations or single images?
I'll assume you are talking about animations. I'm not an artist. But the simple rule is if you made the first image in an animation sequence 50x50 pixels, then the remaining images of the sequence should also be 50x50 pixels. Should and not a must. but it will make the programming issues easier.
Accuracy comes from you.
Something like photoshop would be perfectly fine for creating UI images.
As for accuracy, I'm wondering what you mean. If it means "I want my GUI to fit over my game screen", then simply take a screenshot of your game, and use that as the bottom layer in photoshop. If accuracy means "I want the GUI to look like the default (Windows/Mac/Linux/iDevice) GUI", then you can either use native OS calls, a GUI library, get art from the internet, or draw the assets yourself.
My favorite tool is a whiteboard. If I ever want to make a design "permanent," I just take a picture of it.
To make it clear. Use can use Photoshop or any other image-manipulation or image-editor for 'mock-ups'. This helps you decide the color of each element of your GUI and the look-n-feel of it.
To actually design your UI, you will need a custom application, i.e. not Photoshop, to create your GUI and save the 'layout' (and associated images or sprites) to a file, which can be loaded by the game you're targeting the UI for.