Can anyone give me advice as what the best kind of work experience to do to get into medical school and any other tips to give me a better chance of getting in
My mum works in a doctor's surgery/medical centre and they regularly have GCSE/A-level students doing their work experience there. They obviously do a lot of filing and tea-making, but the doctors do teach them stuff as well and they can watch the minor operations if the patient doesn't mind.
Joining St John Ambulance or the Red Cross and going out on public duty is a good way to show your interest. Or Scouts/Guides - med schools are keen on students who give something back to their home communities.
To get into medical school you'll need exceptionally good exam results before you can even be considered. (At the most popular medical schools even some candidates with 4 A-grades at A-level don't get accepted). It's also very important to select the correct subjects at A-level. See the various links from here for more details: http://www.learndirect-advice.co.uk/helpwithyourcareer/j obprofiles/category28/
The best way to increase your chances of getting into medical school would probably be not to apply straight from school (or college). A well-spent gap year is likely to be far more impressive than any particular type of work experience. Have you considered the Youth Volunteering scheme with VSO? : http://www.vso.org.uk/volunteering/youth/index.asp