This sort of scheme has been going on for a while, I work in a charity shop and we had 6 people on this scheme. They do 30 hours a week, we had to fill in a sheet to say what they have done and someone checks up on the once a week, scheme lasts 4 weeks, 3 have stayed on, two were a nightmare and didn't want to be there and one resented being made to do it and left, her money was stopped. There is also a scheme for 16 to 19 year olds 25 hours a week min pay for 6 months.
The main problem is if they don't want to do it they make life very difficult for the other staff.