Shop Assistants Vacancies

Jobs for 16 year old in the UK??? Please help!!!?
Ok so I just turned 16 three months ago and would love to do a part time job BUT I dont know where to start.What do I do? Where should I apply and how? Do I just post my CV at the stores or should I go in and ask?
Is is right to ask the shop assistants whether ther is a vacancy suitable for me?
There arent many in the newspaper apart from the newspaper rounds which I personally dont like.
I also want a job which gives a decent work experience.Can I work with a docor as an assistant or a dentist as I would like to seek a career in medicine in the future.
Plus I am currently doing GCSEs which are going great and am aiming for A*s and As but havent completed them so do I just write the target grades on my CV.
Please suggest whether there are any suitable stores..Thanks.
Well, you can work at shops eg retail. or like mc donalds and kfc. you can also babysit because then you can basically choose your own hours and parents will choose a 16 yr old over a 13/14 y/o xx hope this helps xx