Thanks for the pointers @generix
Dual-boot seemed to be the issue, fresh install of 18.04 (secure boot off) and install the 418.43 drivers, reboot and all working fine now. This worked without the need of the cuda libraries.
Thanks all :)
@greg.chance
You mentioned above that “dual-boot” was the issue. When you finally got the NVIDIA drivers working, was that with dual-boot windows and ubuntu? Or did you just decide to boot it only to Ubuntu 18.04?