Time Machine back up and bootable drive
I have a late 2015 iMac with a drive that is slow and probably on its last legs. I also have a 2Tb Time Machine that is not able to do a full back up due to it being full. It apparently is not deleting the older backups to allow for a new one.
I am looking at buying a 2TB SSD drive to serve as my new TM backup disc and also a bootable drive for normal use. I want to replace the original internal disc with a new reliable and much faster one.
My question is how do I go about this?
Do I simply do a full backup to the new SSD then convert it to a bootable drive for daily use? The goal is really to have a new bootable drive, the initial back up serves only for migration of original disc data to the new one.
Thanks for any advice