Your moon pic is nice Ghillies
Yes, high ISO best avoided, and not necessary for moon shots. If your camera has spot metering use that mode and meter on the moon, not the dark sky.
If you want to include a bit of scenery in your shot but keep detail in the moon, you will need to use a long exposure for the dark land, then combine it with another shot, taken to expose for the moon. Tricky, but worth it