The impact of being on a debt management program is that while your on the program you’re considered an R7 credit rating.
Which means that you are on a voluntary debt repayment program. So while your on a program your promise to the creditors who have granted you interest and penalty relief while on the program is that you will not take on anymore unsecured credit.
When you graduate or come off the program you will typically remain an R7 for 6 months to 2 years, no more than 2 years statutorily. And from my experiences you will probably be back to credit granting status within 6 months to a year.