thanks Ray have managed to fix it now
On that same page, there is a plugin on line 806 (which is referenced from admin_cms/plugins/colour_options.php) which, when a colour option is selected from the drop down then shows the relevant associated colour options.
When selected, those colour options should update the join table (colours_available) with columns AvailableID, AvailableColourID and AvailableProductID
Am not sure what update I need to do to get this working?
Thanks