Both my husband and I find that Normison (or any Temazepam, which is the generic name of it) does not work so well to help us sleep. In particular I find that it does not help me go to sleep and it makes me feel more tired the next day than I would have been without it.
Zolpidem Tartrate, which I believe is called Stilnoct in the UK, works better and neither of us need the full dose. He and I only ever take half of the normal dose (10 mg is the normal dose). I do not know what UK CAA's position is on this med, but I was told that CASA (Australia) approves of its use by flight crew. The half life is very short, and it is not supposed to leave you drowsy the next day. However I must point that I personally feel that it slows down my already-slow brain somewhat the next morning. If you take this one, make sure that you can get to bed quickly, as it can start to work rapidly.
Another option that I came across in this forum was called Sonata (Zaleplon). I have not personally tried this one as I do not believe it is available over here, although I think it is in the UK. It is said to be the shortest acting sleeping pill currently available.
So, you may want to check out Stilnoct and Sonata.
However as others said, try other methods of helping your sleep before you resort to medications. You say that your sleep has become more erratic since a relationship break-up. This suggests that there may well be a psychological cause to your sleep problem that may need to be addressed. I find that if I am well and truly stressed, no medicine will help me sleep. Also remember that sleeping pills do not solve the underlying cause of the problem and should not be used long term. However, it can gently help you back into a proper sleeping pattern and get you out of ‘non-sleeping’ habit.
One very important thing is to remember that the more stressed you feel about not being able to sleep, the less you sleep!!
Good luck, and if you want more information about any of the meds mentioned, I’m happy to post some links.