If you type 'DAFNE' in the forum search facility you'll find 100's of posts from members who are DAFNE graduates, I did it 4 years ago and like most people found it extremely helpful.
As for time-off, you can ask the DAFNE team for a letter to give to your employer which explains why you need the time off and a brief summary of the benefits of the course, your employer can refuse the time off and doesn't necessarily have have to pay you, if they agree, some people are lucky and get the time off without taking holidays and others not so lucky.
Hope you enjoy the course!