The hospital where I did my shadowing (and now currently work as a HCA) had a designated person for dealing with work experience. Try to find out if there is somebody like this at your local hospital(s).
Have you tried your GP? Or asking them if there is someone that they know who would be willing to let you shadow them. As some local GP surgeries can be a bit picky I am led to believe.
If you start to get really desperate I wouldn't even rule out just going into your hospital and speak to a secretary or ward/clinic reception staff and see if there is someone you can talk to there and then. It's a lot easier to turn people down via phone/email than it is in person and imo it shows determination and initiative that you have taken the next step to progressing this endeavour.