You might find you get stuck on @nightromantic’s suggestion of step 1 when using logical partitions in dual boot scenario’s.
Tried:
mount /dev/sda1 /mnt/root/boot/
Error:
mount: /mnt/root/boot: unknown filesystem type 'LVM2_member'.
Worked through mounting an LVM partition and everthing worked as expected.
Thank you @nightromantic