Using a LiveCD ..... first back up the contents of the present /home somewhere ... then ...
Copy the contents of the present /home to the spare partition, using rsync to ensure it completed correctly.
Next edit the fstab file on the installation to mount the spare partition as the new /home
I would expect everything to be OK on the next boot .... but I have been wrong before

. . .
Yes, I would like to have a separate /home partition, but
I was unable to use sda8 as /home partition during installlation 
Now, when sda8 is ready for use, I must move /home from sda7 to sda8

Why?
Is there something wrong with the partition?
That statement does not give confidence that the new /home will work ...
