Riding the Paris Roubaix route

Hi,
So it's my brothers 40th and I'm thinking I'd like to take him to ride the Paris-Roubaix route some time this year. I've read a few reports of people riding as a what seems to be a sportive, however I was looking at doing it off our own backs. How possible is this and can anyone give me any advice or tales of there experiences please!?

Thanks Mat