Insulin reduces your blood sugars quite rapidly. Depending on how long it takes for you to get to the correct dosage, it could go down fast. And the DVLA's concerned with low blood sugars due to insulin use, because you could quite well kill yourself and others when you're too low to be able to think and react properly. When you're high that's not so much a problem, so not something they worry about. If you go hypo while in traffic though, due to a miscalculation in dosage or a missed meal while having injected for one etc, that could well spell disaster. Before you drive, test. Remember, it's
5 to drive, if you're under that you need to eat something before leaving, or your insurance might not cover any mishaps. No clue about other DVLA things as I don't have a license myself, but I'm sure someone'll be along who knows more.
If you hate needles so much, might I ask, have you tried lowering the carbs in your diet? Then you might not need insulin at all, eventually. Maybe something to mull over, if it is an option for you.
Good luck, and hopefully you'll see someone more useful appear soon.
Jo