Steps i took to get the HP 255 G6 working with mate 18.03;
Update Bios using USB key (updated to version F23)
install mint from DVD (Installing from USB drive seemed to mess up the drives SDA/SDB so that after reboot no OS drive was detected)
Updated kernel after install (applied kernel update on its own, (when I initially tried to apply all updates it crashed/froze and no reboot)
rebooted and all works okay.
Seems to be stable and pretty quick
Bit of trial and error but happy with it now.
Thanks for the assistance