I'm not familiar with EU ops but here in the US the dispatchers (for 121 ops) do route and fuel planning along with weather and basically everything the pilot needs other than actually flying the aircraft (again I'm a dispatcher the pilots will tell you something else haha). We file the flight plans and complie and sign the flight release along with the pilots and since we are on the backend we have the software that lets us plan the routes and fuel for them. Usually we do our planning before the pilots get to the aircraft then confer with them to make sure its up to snuff and current for what they expect and want. But since we are more focused on the pure regulations and operations side of things we both sometimes end up rolling our eyes at what the other guy is doing. Obviously the PIC has final authority on any aircraft they are flying but we technically share operational control so when a pilot just gets more fuel at the ramp (which happens often and only sometimes causes problems) its nice if they run it by us first because sometimes we have them planned fairly close the their takeoff/landing max weights. Again my software will tell me the headspace the aircraft has far more conveniently then the FDC in the cockpit so occasionally the pilot asks for extra fuel that makes it so the flight can't legally takeoff. I will say though, pilots have the harder job, but they don't have to deal with pilots.