A couple of other things to think about.
What "time" are you actually paying for? Take-off to touchdown, take-off to touchdown plus x minutes ( 5-10 minutes added on for taxi time, or hour meter from engine start to shutdown etc.
Also consider how large the circuits are and how much delay you might get at the holding point etc.
If they fly big circuits you will get less landings per hour and thus probably need more hours of circuits.
If there are lots of commercial movements, do ATC sit you at the holding point for ages waiting for the airliner on a 20 mile final, or hold you on downwind in similar circumstances? I learnt at Bristol Lulsgate 20 years ago when it wasnt very busy, but the ATC were also not very good and would keep you waiting forever, either on the taxiway or orbiting somewhere!
Good luck!