All I did was boot the Debian netinstall image from USB. Then I let the installer reformat the SSD and take it over, deleting everything on it. Debian formatted it as MBR and I have basically two partitions - one for the O/S and one for swap.
As I said earlier the setup boots in legacy format, so no need for EFI partitions.
Edited by ebrke, 12 July 2018 - 06:29 PM.