Jon,
I have bled a couple of these systems and it does not sound like your needs it.
There is always a little bit of play if you twitch the wheel side to side as the valves have to do their stuff and you will hear them clicking away when you do this. However if the steering generally feels solid then you are probably fine.
There is one way to tell if the steering needs bleeding and you will need the filler pipe that screws into the top of the helm pump to test this. All you do is undo the filling cap, screw in the fill pipe and then half fill the fill pipe with the correct hydaulic fluid. Then rock the steering back and forth. If the level of fluid in the pipe rises and falls by more that an inch then you could probably do with bleeding it, otherwise you are fine.
It is quite usual for the steering wheel position to alter and if you fit one of those five spoke steering wheels you won't notice it then
Chris