Hiya, thanks for all your replies.
Fixed! I knew it was something I had done or a box I had checked.
For some reason, I have had the "Enable simultaneous RA & DEC corrections" checked in guide settings in MaxIm which has been what has caused the issues. It now calibrates and guides quite well for an AZ-EQ6.
How accurate it is I'm not sure, but it was guiding at RMS X axis 0.253 and Y axis 0.132.