I too am from the uk, When I was your age I too had a fear that I was going to die, I hated going to bed because I thort that I wud not wake up, this brought on panic attacks, each and every time I went to bed and every day I always felt anxious.
I constantly had this fear of dying, this fear brought on anxiety, panic attacks, headaches, which all made me feel that I had a health problem which confirmed in my head the fear that I would die. This went on for prob about a year, doc told me I was Over anxious, which at the time I did not think I was and thought that he didnt have a clue what he was talking about.
It wasnt until someone (who didnt know what I was going through) and through conversation said "when yr time is up, its up" It made me think well yes thats right, then I thought about all the times that I had panic attacks going to bed because I thought I was not going to wake up, and yet I woke up every time.
What am trying to say is sometimes (if we are medically healthy) for whatever reason we develop a fear of some sort.
When I look back I think my fear was not because I was going to die, It was my lifestyle
at the time, I was in a loveless relationship, had two children to look after and I think I was lonely, frustrated and unhappy with my life.
Unless you have been told that you have a life threatening disease, then you can over come your fear with family support and getting professional help, (if needed), you can over come this just get the help that you need and learn to believe in yourself.
Good luck
Keep yr chin up
chris
You might want to look into talk therapy, really the only option you have. Luckily this fear has only manifested itself, so I'm sure you can overcome this quickly. I used to have this fear as a child, and I know it can be horrible. Speak to your doctor and get a referral. You may also want to check into a phobia group in your area.