At Imperial we are really lucky that everyone gets a guaranteed place on an intercalated BSc course, hence why we are here for a hefty 6 years.
During an intercalated BSc all medical students take a step away from the normal day-to-day life of a medical student and enter the realm of essays and deadlines for a year in 4th year. At the end of year 4 we all gain a BSc in the course of our choice. Pretty cool. We spend September-Feb in lectures and then have our exams, and then we get to complete a research project (or a short course) for a few months.