...to get back to the original bloke's question: If you fly the Hurricane and Spitfire, they both have rudder trim, which could remedy your problem somewhat.
Ideally, for cancelling any banking, there would be aileron trims (which cancels auto-movement exactly along the axis you have problems with), but neither the Hurri nor the Spit do have that - so you have to trim (somewhat) around the yaw axis, that is, an axis drawn from your pilot's head down his spine and so on (not necessarily
exactly centered on the pilot, for the nitpickers
)
So, you may see some problems already when imagining that - yaw trim
does cancel engine torque, but you:
a) may have to be trimming rather boldly - it's not just a few 'clicks' if your engine runs at full throttle, more like a few ten clicks.
b) may introduce some yaw in the other direction which let's you drift off-course over time and which you should consider because of that. So either you don't trim as hard and do the rest manually, or correct your course from time to time (this may be rather oftern) or you reduce throttle, which helps on engine torque and reduces the problem to begin with.
Hope that helps.
P.S.: The Hurri and Spit have an instrument for that in the cockpit: the turn & bank indicator. It's the instrument which has two hands, looking somewhat mirrored along the horizontal axis. The lower hand gives your banking angle and the upper hand helps with correcting excessive yaw: If the hand is in the middle, you've canceled any auto-yaw and you should fly straight along the course you've set (not considering wind etc.), albeit probably your automatic banking may not be entirely canceled, as described above.