I have had a DMP since having health problems after graduation and big student debts. I have now over ten years paid off over 6.5K and have less than 2K left! I feel really pleased I did this now. I was so worried at the time my credit score would be ruined, but now it seems good 9I think after 6 years it is not on the record anymore) I am with pay plan, a free service like step change.
It meant having a simple bank account and debit card and no cards / loans for years, but for me that actually helped a lot and was far less stressful. i would recommend it to anyone with debts struggling especially with MH problems and stress. The letters stop, the interest is frozen, you actually make a dent in what you owe, even if as with me, that was £30 a month over years. It has really been life changing.