It definitely seems unusual to be prescribed gliclazide with type 1.
Perhaps it has something to do with trying to manage the lowered amount of insulin your body is producing as you are in teh honeymoon period and still have some insulin producing cells.
There are many different reasons for insomnia.
It could be the stress and concern of diabetes and seeing your BG rising.
It could be related to your BG.
For me, if I wake in the middle of the night, the first thing I do is to take a BG reading. Nine times out of ten, my BG is too high or too low and once I treat this (with insulin or glucose), I am able to go back to sleep without any trouble.
Or, it could be something else.
I agree with
@EllieM that, if the insomnia is related to your high BG, the insulin should help.
My only suggestion in the meantime is to try eating low carb until then. This should help keep your BG lower or at least avoid high spikes.
Once you get the insulin you should be able to go back to your usual diet although some people with t1 choose to maintain a low carb diet.