If you are just taking 2 units of lantus, I wouldn't bother waking up to check. It is a very slow insulin. The usual doses last 24 hours or more. With a smaller dose like that, I suppose it could possibly be gone in less than 10 hours, but that is not enough to do the slightest bit of damage. (imho of course)
You could hardly get more than a fifth of a unit an hour going into your blood stream. That is just not enough to cause any kind of serious hypoglycemic episode. I would just relax and get some rest.
I think it's a great idea to start on insulin while your requirements are so small. That makes using it safer, and takes a load off the pancreas.
I have never used the mixed insulins, and really don't like that idea. That's when you have to eat at a certain time after injecting. Anything can happen in a day and does quite often. I can't count of being able to eat at a certain time.