Not wishing to 'diss' GT6's alternative route, but I believe there are roadworks up by the Carrefour, so it might be wiser to avoid that area.
Plus, whenever I've tried to be clever and take that route back, I've never been able to spot the tiny exit at Tertre Rouge and have ended up going down to the roundabout at the first 'chicane'. I am, of course, a Lamer.