lloyds chemist diabetes blood glucose test just as good as

[zippitippitoes]

...a gp appointment?

It's just a snapshot..is it worth doing?

And what time of day would be most likely to give a sensible result?

it gives a snap shot.
if you have serious concerns about diabeties you should go to your GP and have a fasting blood glucose done.
a number of things can affect the pinprick test however it would be more inclined to give a false positive. IE you have just eaten or you are very very stressed. even the soap you wash your hans with can affect the reading.
I would look to get one done just before you eat. this is when your blood sugar should be failry low. if its raised at this point then you do need refered.
sorry if this is a bit garbled, are you worried?