Although this website focuses more on STEM subjects than medicine, I have occasionally posted about several opportunities aimed at students interested in medicine.
A new website set up to focus more on these opportunities is Future Medics which has a very handy map-based list of medicine-related opportunities. They are also a good site for advice on work experience, recommended reading, and current news related to medicine.
Students interested in applying for medicine at university may also be interested in some biology related courses too, many of which are listed on this website.
