I went on the DESMOND course within a week of diagnosis, as they had a cancellation, but some have to wait months.
I thought at the time it was useful for me as I was terrified, fearing I was on an inevitable course to increasing failing health and complications.
It did reassure me a bit. But the dietary advice given isn't good for Type 2 diabetics or pre-diabetics. The NHS 'Eatwell Plate' is pushed, and we were told we needed to continue eating starchy carbohydrates. I learnt more after finding this forum, by mistake.
The Nurse conducting the course recommended the Diabetes UK forum, but I found this one.
I think you will learn more about controlling your condition on here than from the DESMOND course.