Hi Jill,
There are alot of variables. First things there is a margin of error in what a meter gives you, that's to say it could be X percent either side of the reading that you are given. Secondly the blood used for this kind of test is capillary blood and differs from one part of the body to another. I have tested with the same BG meter from the same sample from the same finger and got two different results.
As for control solutions no chemist supplies it unless it comes within the bundle that you get with the machine, If you call the manufacturer you should be able to get some sent out to you free of charge, I recall when my Roche meter went dead on me a few years ago I called up and got some batteries for nothing, so one can assume that the same applies to control solutions as they make all the money from the strips.
Tom