Hi there I'm a couple weeks into Medicine at Cardiff. As you may know each medical school has it's own course structure and teaching style so it would be impossible to give you a generic answer. What I will say is that here in Cardiff it's a mix of Lectures (they call them plenaries), small group teaching sessions, Dissection from 2nd week for learning anatomy, Clinical skills and after Christmas we get to go on placements and begin Case Based Learning. Cardiff is only one medical school though and what you have to bear in mind is that all medical schools have different teaching methods e.g some have Problem based learning some do prosections and some may not have early patient contact etc.....
I think at most medical schools you have 2 exams at the end of the year which you must pass to proceed. These are really hard exams but are multiple choice and the pass mark is around 50%. There are usually mocks in January aswell which make sure your keeping up.
One thing I can say about medical schools is that it is very much independent learning in that your not really offered that same level of support as from A levels (i.e your not spoon fed as much). So you have to self direct your own learning.
Also what you also have to remember is that the top people from each school/college usually go into medicine and that means peer pressure is far more evident and it's much harder and close to impossible at times to know more than your classmates. BUT even though medical school is tough it is very manageable and should endeavour to play at least one sport to keep fit and healthy/socialise and take your mind away from medicine at times. Also you don't feel the pressure of getting into medicine whilst your a student but instead you feel the pressure of keeping up with the work which can be just as intense at times.
I wish you all the best of luck with your medicine application when you apply. It's an absolutely fantastic vocation.
Please don't hesitate to ask any other questions.