How do I go about changing the dialling from Skype only on my Android phone?

You will need to reset your preferences in your Android phone.   

Go into your Settings, then Applications, then Manage Applications.  

Select the 'All' tab and scroll to the current dialer app. 

Scroll down and press the 'Clear defaults' button. 

Now when you select dial, you should be prompted to select a particular app and also have the opportunity to set a new default.