This is an AF flight operated by HOP (I checked on your date to make sure you were not on a FlyBE flight, as normally HOP aircrafts are not used on this route, but there is indeed one flight on Aug 11).
J class will be provided at the front of the aircraft but, compared to AF mainline, there is no seat blocked on regional jets, so you may have a neighbor (seating is 2-2). Seat width and pitch is the same for Y and J, as it is usually for the all Euro carriers. If you want more legroom, select a seat on row 1.
But basically the differences between Y and J in-flight will be only on food & beverages. On the Ground, you have of course the SkyPriority services and lounge access.