Please can someone tell me how to create this new module and what code is required. alternatively if there is a module created on github maybe? Then just how to install it 

To modify base fields in Odoo, you need to create a custom module and use Python code to make the changes. This is because the fields that are part of the core Odoo system (known as "base" fields) cannot be modified directly through the studio user interface. By creating a custom module, you can write the code needed to make the desired changes to the field, and then install and activate the module to apply the changes to your system.