I'd like to centre the point of rotation to the dead centre of the art board. Is this possible
You can place guides to mark the artboard center, then place your rotation point at that center.
You could click a single anchor point at the center of the artboard and use that as a point of rotation.
You could draw a rectangle the size of your artboard and rotate the rectangle (along with anything inside it).
Other than this I'm not aware of any automated method to tell rotation tools and features to use the artboard as a basis.
Your first step is going to be to open the "Edit Artboards" dialog box in Illustrator. Click "File" from the menu and top, and click "Document Setup". From the box that appears, click on the "Edit Artboards Buttton". You can then click on the artboard that you want to rotate. Once you've selected your artboard, click on the center anchor point (see screenshot below) and then click either the landscape or portrait setting to change the rotation.