Not sure if this would work, but how about trying a 24 hour fast, to get your insulin back to a good level? Just take your lantus, and eat beef and lettuce (boring, but hunger-quenching) during the day. Monitor your levels. It would also indicate if your Lantus is working correctly. Then once you are back on course, keep a bit of tight control for a while.
Bad control can cause problems with your teeth/gums, so that is probably causing your ulcers etc. My dentist is almost as well informed about diabetes as my specialist is, which is great, and he keeps urging me to get my control to be fantastic, to prevent future problems with gum disease.
I'm always surprised by the high dosage of Lantus that UK peeps seem to be on. I was on 26 when I moved to France, and that was reduced down to 13 straight away. Are you sure you are on the correct dose now? It'll change if you lose weight, or put weight on.
Are you falling low so taking food to get back up, and maybe taking too much which leads to high sugars, so taking corrective doses, which leads to hypos etc etc etc?
I'm shocked that you can't get an appointment with the nurse sooner than Jan, too
Move to France. :mrgreen: