On the OCU Copilots must complete a good 10 (odd) assessed 4hr sims before being put in the LHS of the jet. We then 'trust' them to get it right with the NWS.
The very first Nimrod OCU trip is done from the LHS. In fact as a co pilot you only do 2 RHS trips on the whole course. And the only requirement to go from being a co to a P1 is a RHS cx!
It might sound a bit odd to those on the outside looking in, but ultimately very, very few cos don't go on to be P1s. What's more if you don't get that P1 slot there's no way you'd leave the stn with a CFS rec. In essence I don't see a problem with cos operating in either seat.