Thank you very much Pavel. I've just downloaded all 3 files.
I'll look around for documentation on how to unpack and use bpi-bootsel to choose this kernel and bootloader.
I read on armbian forum that people are working on the kernel code also
https://forum.armbian.com/index.php/topic/2884-the-new-banana-pi-m2-ultra/
UPDATE
OK, i've copied the files across into a directory, and had a look at boot-sel. When I run it, it shows a list of images in the /usr/lib .... directory. I don't know how to select all 3 files so they are selected and installed as default. Can you help?