John, if your not 100% happy with the AF accuracy and as you say, if the camera cannot be calibrated either, here are a couple of options...
Assuming you have a DSLR, then the first would be to manual focus and use the "Live View" mode if your camera has this function. This will show you exactly what the sensor is seeing, leaving you in no doubt if the image is sharp or not. Some cameras have a magnifying funtion too whilst in this mode, which can make it even easier to spot when everything is "bang on". One word of caution though, it's not that easy when your hand holding the camera, best on a tripod.
The second is to manual focus again, but use the viewfinder screen instead. This is faster than option one above, but may not be as accurate, as you have to rely on the manufacturer matching the focus planes of the sensor and viewfinder screen. Normally this is a given, but you may wish to try shooting some text, just to see how it looks in the viewfinder whilst comparing it with the image on the display screen. Use a tripod when you try this, that way everything stays in the same place and makes it a whole lot easier to view.
Not really sure what else you can do with a fixed lens camera, apart from using the "Live View" function or sending it back to the maunfacturer for correction.