nice work and a good haul for the night Simon
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There is an open cluster near M47 identified as NGC 2423 - not sure if this is the one you saw!
When you get out to your dark sky site be sure to check out the planetary nebula in M46 at high power and you should be able to notice its annular (circle) appearence. Your 12" dob should show the planetary nebula as clear as a bell.
When it comes to observing I have found I usually highlight one or two new objects I want to find and observe (more if I am going to be out for most of the night) and if multiple I try to make them in different parts of the sky. I usually return frequently to the highlights of the sky throughout the observing session - objects that positions are burnt into my memory (revisiting old favourites if you like). Sometimes I will pick an area of the sky such as a constellation and while holding the Cambridge Star Atlas in one hand I just wander from one DSO to the next. Most of my observing sessions also involve sliding in the 31mm Nagler into the focuser and just touring an area to see what I can find. You are totally right about having some sort of plan, but I wouldn't let it rule your observing or make the plan too extravagant. You can always find targets on the fly with some maps if you want to "fill in time".
Hope you have clear skies at your dark sky site.