Thank you for your ideas and links for support and yes it is a storage issue.
I have been spending more money on iCloud monthly storage as Apple told me this would resolve my problems however it hadn't.
Finally I ended up deleting a lot of my photo's, video's off and emails off my iPhone SE which freed up space.
It took a few hours for the download to finish and afterwards I was able to backup my iPhone to my computer.
All this because I want to upgrade and get a new iPhone and be able to transfer all my data from this phone to a new iPhone 12 mini or the new iPhone SE with more power and functions than this old iPhone SE. Thank you.